Service

Caddy 1996 , Polo Classic 1996 ➤

Mono Motronic injection and ignition system
Engine ID 1F ADZ

Edition 11.1995

AG. Volkswagen AG d
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Service Department. Technical Information

 Service
List of Workshop Manual Repair GroupsList of Workshop Manual
Repair GroupsList of Workshop Manual Repair Groups
Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system

Repair Group
01 - Self-diagnosis
24 - Mixture preparation, Injection
28 - Ignition system

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Technical information should always be available to the foremen and mechanics, because their careful
and constant adherence to the instructions is essential to ensure vehicle road-worthiness and safety. In
addition, the normal basic safety precautions for working on motor vehicles must, as a matter of course,
be observed.

All rights reserved.

No reproduction without prior agreement from publisher.

Copyright © 2011 Volkswagen AG, Wolfsburg 00056405520

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995

Contents

01 - Self-diagnosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
1 Self diagnosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
1.1 Self diagnosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
1.2 Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
1.3 Technical data of self diagnosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
1.4 Connecting fault reader V.A.G 1551 and selecting engine geelectronics
n AG. Volkswacontrol
gen AG unit . . . . . . . .2
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1.5 Interrogating fault memory . . . . . . . . . . . . . . . . .b.y V. o.lk. . . . . . . . . . . . . . . . . . . . .n.ot. g.u. . . . . .3
a
1.6 Fault table . . . . . . . . . . . . . . . . . . . . . . . . . . .or.ise. d. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .ra.n.te. . .4
e
1.7 Erasing fault memory . . . . . . . . . . . . . . . a.u.t . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .or.7
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ac
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1.8 Final control diagnosis . . . . . . . . . . . . . .s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

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1.9 Coding control unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10

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1.10 Erasing values learnt by engine electronics control unit . . . . . . . . . . . . . . . . . . . . . . . . . . . .11

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1.11 Read measured value block and basic settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
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1.12 Display group overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12

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24 - Mixture preparation, Injection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15

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1 Mono-Motronic injection and ignition system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15

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1.1 Mono-Motronic injection and ignition system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
1.2 Fitting locations overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15

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1.3 Servicing injection part . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
1.4 Servicing injection unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
l purpos

1.5 Safety precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31

1.6 Rules for cleanliness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31

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1.7 Technical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32

m

1.8 Idling speed check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32

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tion in
1.9 Checking Lambda probe and Lambda control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33
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1.10 Checking Lambda probe heating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35

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1.11 Checking engine operating mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36
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1.12 Checking throttle valve positioner . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37

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1.13 Checking and adjusting idling switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38
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1.14 Checking sender for throttle valve positioner . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42
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1.15 Checking throttle valve potentiometer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43
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1.16 Checking coolant temperature sender . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45
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1.17 Checking intake air temperature sender . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48
1.18 Checking injector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .50
1.19 Checking speed signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52
1.20 Checking control unit voltage supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .53
1.21 Checking air conditioner and air conditioner compressor signals . . . . . . . . . . . . . . . . . . . .55
1.22 Matching automatic gearbox control unit and throttle valve potentiometer to one another . . 56
1.23 Checking signal for automatic gearbox control unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .56
1.24 Matching engine electronic control unit to electronic immobilizer . . . . . . . . . . . . . . . . . . . .58
1.25 Checking fuel pressure regulator and holding pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . .59
1.26 Checking intake air system for leaks (unmetered air) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .61
1.27 Checking intake air preheating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .62

28 - Ignition system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .64

1 Mono-Motronic injection and ignition system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .64
1.1 Mono-Motronic injection and ignition system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .64
1.2 Servicing ignition part . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .64
1.3 Safety precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .67
1.4 Adjustment data, Spark plugs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .68
1.5 Installing distributor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .68
1.6 Checking and adjusting ignition timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .69
1.7 Checking ignition timing control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .71

Contents i
 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic winjection
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AG. Voland
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1.8 Checking
rise
d Hall sender . . . . . . . . . . . . . . . . . a.ra.n.t . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .71
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1.9 ho
Checking ignition transformer . . . . . . . . . . . . . . e. o.r a. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .73
aut
1.10 sChecking
s
ignition transformer output stage . . . . . . .c . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .73

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ii Contents
 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995

01 - Self-diagnosis

1 - Self diagnosis
1.1 - Self diagnosis

Note:

The self-diagnosis monitors only a part of the injection and ignition system. For fault finding the binder "Fault
finding engine" must also be used in every case.

1.2 - Function

The Mono-Motronic control unit (J257) for the ignition and fuel injection
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The faults stored can be read-out with the fault reader V.A.G 1551 or the vehicle system tester V.A.G 1552 =>

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The fault memory must be erased after the fault(s) has been eliminated => Page 7 .

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A fault relating to the function of the Lambda control system can only be interrogated after a test drive of at

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least 10 minutes duration.

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Faults which only occur sporadically will have the addendum "sporadic fault" on the print out. These faults will
be indicated on the display by the addendum "/SP". The cause of sporadic faults can be e.g. a loose contact
or a brief open circuit. If a sporadic fault does not occur again within 10 engine starts, it will be erased from the

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fault memory.
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1.3 - Technical data of self diagnosis

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◆ Fault memory: Non-volatile memory and volatile memory1)

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◆ Rapid data transfer

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=> Page 2 ; connecting fault reader V.A.G 1551 and selecting engine electronics control unit

Selectable functions

The prerequisites for selecting the desired functions can be taken from the table.

1.1 - Self diagnosis 1

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995

Function Prerequisite
Engine station‐ Engine running
ary, ignition at idling speed
switched on
02 Interrogate fault ---1) x
memory
03 Final control di‐ x ---
agnosis
04 Introduction of x x
basic setting
05 Erase fault - x n AG. Volkswagen AG do
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06 End output x x orised ran
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08 Read measured x s ax
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10 Adaption1) x ---

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1) If the fault memory is interrogated with the engine stationary, the fault "Hall sender -G40, no signal"
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will be displayed even if there is no fault present.

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1.4 - Connecting fault reader V.A.G 1551 and selecting engine electronics control unit

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Special tools, testers and auxiliary items
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◆ Fault reader V.A.G 1551 with cable V.A.G 1551/3

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Note:
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The vehicle system tester V.A.G 1552 can be used instead of the fault reader V.A.G 1551, however a print-out

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is not possible.
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Check conditions
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• Fuse 21 OK.
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• Battery voltage at least 11 V
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• Earth connections on gearbox or engine OK.
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• Air conditioner switched off
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Work sequence

- -> Fold down left shelf.

- Connect fault reader (or vehicle system tester) with cable V.A.G 1551/3.

After the fault reader has been connected:

2 01 - Self-diagnosis
 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995
- Depending upon desired function:
Switch on ignition
or
Start engine => Page 1 , Table "Selectable functions".

Notes:
◆ If the display does not indicate as described in the work sequence:

=> Fault reader operating instructions

◆ If due to an input fault "Fault in the data transfer!" is displayed, pull wire off fault reader, reconnect and repeat
work step.

- Operate fault reader taking into account the information on the display:
- Input 1 for "Rapid data transfer".
- Input 01 for address word "Engine electronics" and confirm with Q.

-> The fault reader V.A.G 1551 display will show the control unit identification, e.g.:
6K0907311B 1.6l R4 MONO 1.2.3
DGC
Coding 01

◆ 6K0 907 113 B = Part No. of the control unit

◆ 1.6 ltr. = Engine capacity
◆ R4 = Type of engine (4 Cyl. in-line engine)
◆ MONO 1.2.3 = System designation and version
◆ DGC = Programme level number
◆ Coding 01 = Coding variants

- Checking control unit coding => Page 10

- Press ⇒ key.

-> Indicated on display:

Rapid data transfer HELP
Select function XX
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1.5 - Interrogating fault memory

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Special tools, testers and auxiliary items

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◆ Fault reader V.A.G 1551 or vehicle system tester V.A.G 1552 with cable V.A.G 1551/3
ole,

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urposes, in part or in wh

Work sequence
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- Connect fault reader V.A.G 1551 (V.A.G 1552) and select engine electronics control unit (address word 01);
selection is carried out with engine idling.
rrectne

=> Page 2
ss

Only when engine does not start:

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- Operate starter for approx. 6 seconds and then do not switch off the ignition.
mer

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Note:
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When the fault memory is interrogated with engine stationary without having operated the starter for at least 6
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seconds, the fault "Hall sender -G40, no signal" will be displayed, even if no fault is present.
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- Switch on fault reader printer with the print button. The warning lamp in key lights up.
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1.4 - Connecting fault reader V.A.G 1551 and selecting engine electronics control unit 3
 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition
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Rapid data transfer HELP oris eo
Select function XX th
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- Operate fault reader taking into account the information on the display:

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- Input 02 for "Interrogate fault memory" function and confirm with Q.

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-> The number of faults stored or "No fault recognised!" will be shown on the display.

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X Faults recognised!
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If one or more faults are stored:

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The stored faults will be displayed and printed out one after the other.

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-> After the stored faults have been printed out, the display will show:
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Rapid data transfer HELP

Select function XX

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- Input 06 for "End output" function and confirm with Q.

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- Locate and eliminate faults printed out as per fault table => Page 4 .
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- Erasing fault memory => Page 7

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If no fault is stored:
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- Press ⇒key.
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-> Indicated on display:
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Rapid data transfer HELP by c
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- Input 06 for "End output" function and confirm with Q.

Note:

If the self-diagnosis has not detected a fault, use the appropriate fault table in "Fault finding engine" binder for
further fault finding.

1.6 - Fault table

Notes:

◆ The fault table is listed according to the 5 digit fault code on the left.
◆ Explanation of the fault types (e.g. "open circuit/short circuit to earth"):

=> Fault reader operating instructions

◆ If components are indicated as being defective:

First check the wiring and connections to these components as well as the system earth connections ac‐
cording to current flow diagram. Only when no fault can be found, renew component. This is particularly
relevant if the faults are indicated as "occurring sporadically" (SP).

V.A.G 1551 print-out Possible fault cause Fault elimination

No fault recognised! If a fault is present: Continue fault finding using fault table in
Fault not recognised by self diagnosis "Engine fault finding" binder.
00282
Speed sender G68 Speedometer (G21) defective - Check speed signal
=>Page 52
no signal Wiring open circuit

4 01 - Self-diagnosis
 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995

V.A.G 1551 print-out Possible fault cause Fault elimination

If no display appears eon speedometer:
n AG. Volkswagen AG - Continue fault finding according to MFI
Speedometer sender olkswag (G22) defective dfault
oes finding programme in "Current flow
not
ed byV diagram,gu Electrical fault finding and Fit‐
ara
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nte binder.
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00282 ss
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Throttle valve positioner V60 Wiring open circuit - Check V60 =>Page 37

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implausible signal V60 defective

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V.A.G 1551 print-out Possible fault cause Fault elimination

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00515

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Hall sender G40 G40 defective - Check G40 =>Page 71

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es, in part or in w

no signal Wiring open circuit

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00516
Idling switch F60 F60 defective, always closed - Check F60 =>Page 38

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Short to earth Wiring has short to earth
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Open circuit/short circuit to positive F60 defective, always open - Check F60 =>Page 38
Wiring open circuit

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Accelerator cable incorrectly - Adjust accelerator cable

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adjusted => Repair Group 20; Removing
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and installing parts of the fuel

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c

supply system; adjusting accel‐

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erator cable
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V.A.G 1551 print-out Possible fault cause Fault elimination
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00518 t. Cop py
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Throttle valve potentiometer G69 gh ht
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Short to earth Wiring/G69 has short to earth - Check G69 => Page 43
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Open circuit/short to earth Wiring open circuit
G69 defective
Open circuit/short to earth Wiring open circuit
G69 defective
Short to positive Wiring open circuit
G69 defective
implausible signal G69 defective

V.A.G 1551 print-out Possible fault cause Fault elimination

00522
Coolant temperature sender G62 defective - Check G62 =>Page 45
-G62
Wiring has short to earth
Open circuit/short to positive G62 defective
Wiring open circuit
implausible signal G62 defective
00523
Intake air temperature sender G42 defective - Check G42 =>Page 48
G42
Short to earth Wiring has short to earth
Open circuit/short to positive G42 defective
Wiring open circuit

V.A.G 1551 print-out Possible fault cause Fault elimination

00525

1.6 - Fault table 5

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995

V.A.G 1551 print-out Possible fault cause Fault elimination

Lambda probe G39 G39 defective - Check Lambda probe and Lambda control =>Page
33
No signal Wiring open circuit
Short to earth G39 defective
Wiring has short to earth
Short to positive G39 defective
Wiring has short to positive
00532
Supply voltage1)
Signal too low Battery voltage below 10.0 V - Check battery

1) Fault recognition: Motronic control unit (J220) checks voltage after engine has been running for 3 minutes

V.A.G 1551 print-out Possible fault cause Fault elimination

00537
Lambda control1) Lambda probe heating defective - Check probe heating voltage sup‐
ply
=>Page 35
Regulating limit exceeded - Check probe heating for continuity
Exhaust system leaking between - Check exhaust system
cylinder head and catalyst
Misfiring - Check ignition part components
=>Page 64
Fuel pressure to low n AG - oCheck
. V lkswagenfuel
AG pressure regulator
wage =>Page 59 does not
olks
yV gu
Regulating limit not reached Fuel pressure to high ed
b ara
nte
oris eo
Activated charcoal
ut
h filter solenoid - Check N80 ra
sa
valve 1 N80 sleaking, sticking =>Page 8 ; Final control diagno‐
c

ce
sis
le
un

pt
an
d
itte

y li
1) After repairing the faults the values learnt by the Mono Motronic control unit must be erased => Page
rm

ab
pe

ility
11 ; Erasing values learnt by engine electronics control unit
ot

wit
, is n

h re
V.A.G 1551 print-out Possible fault cause Fault elimination
hole

spec
00561
es, in part or in w

Mixture adaption1) Fuel pressure not OK - Check fuel pressure regulator t to the co
=>Page 59
Adaption limit exceeded Misfiring - Check ignition part components
rrectness of i

=>Page 64
l purpos

Adaption limit not reached

Exhaust system leaking between - Check exhaust system
nform

cylinder head and catalyst

ercia

00670
m

a
com

tio

Throttle valve positioner sender G127 G127 defective - Check G127 =>Page 42
n in
r
te o

no signal Wiring open circuit

thi
s
iva

do
r
rp

cum

1) After repairing the faults the values learnt by the Mono Motronic control unit must be erased => Page
fo

en
g

11 ; Erasing values learnt by engine electronics control unit

n

t.
yi Co
Cop py
ht. rig
V.A.G 1551 print-out Possible fault cause Fault elimination
rig ht
py by
co Vo
by lksw
17978 Prote
cted AG.
agen

6 01 - Self-diagnosis
 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995
. Volkswagen AG
gen AG does
V.A.G 1551 print-out Possible fault cause olks
wa Fault elimination
not
byV gu
Engine control unit blocked The electronic ise immoblizer control unit
d - Match theaengine
ran
tee
electronic control unit
(J362) has or
hblocked the Mono Motronic to the electronic
ut oimmobilizer
ra
control sunit
sa Check electronic immobilizer:
c
=> Repair group 96; Servicing electronic

ce
e
nl

pt
immobilizer

du

an
itte
Then start engine and erase the engine

y li
erm

ab
control unit fault memory

ility
ot p
65535

wit
, is n

h re
Control unit defective Components in Mono Motronic control - Renew J257 =>Page 19 , item 2
hole
unit (J257)

spec
es, in part or in w

t to the co
1.7 - Erasing fault memory

rrectness of i
l purpos

Special tools, testers and auxiliary items

nform
ercia

◆ Fault reader V.A.G 1551 or vehicle system tester V.A.G 1552 with cable V.A.G 1551/3
m

at
om

io
Test conditions

n
c

in t
or

his
te

• Fault eliminated
a

do
priv

cum
for

Work sequence

en
ng

t.
yi Co
Cop py
- Carry out road test of at least 10 minutes duration.
t. rig
gh ht
yri by
When doing this cop Vo
by lksw
- The coolant temperature must reach at least 80 °C, cted agen
Prote AG.
- The engine speed must be increased to at least 3000 rpm,
- The accelerator pedal must be floored briefly.
- Connect fault reader V.A.G 1551 (V.A.G 1552) and select engine electronics control unit (address word 01);
selection is carried out with engine idling.
=> Page 2

-> Indicated on display:

Rapid data transfer HELP
Select function XX

- Input 02 for "Interrogate fault memory" function and confirm with Q.

-
Rapid data transfer HELP
Select function XX

-> Press ⇒key until all faults still stored have been displayed and the display reads:
- Input 05 for "Erase fault memory" function and confirm with Q.

-> Indicated on display:

Rapid data transfer
Fault memory is erased!

- Press ⇒ key.

-> Indicated on display:

Rapid data transfer HELP
Select function XX

- Input 06 for "End output" function and confirm with Q.

- Carry out a further road test and interrogate fault memory again. No faults should be shown.

1.6 - Fault table 7

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995

1.8 - Final control diagnosis

The final control diagnosis activates the following components in the stated sequence:

1. Throttle valve positioner (V60)

2. Intake air preheating relay (J81)

3. Activated charcoal filter solenoid valve 1 (N80)

Special tools, testers and auxiliary items

◆ Fault reader V.A.G 1551 or vehicle system tester V.A.G 1552 with cable V.A.G 1551/3
◆ Test box V.A.G 1598/18 n AG. Volkswagen AG do
◆ Hand multimeter V.A.G 1526 or multimeter olksV.A.G
wage 1715 es n
ot g
◆ Diode test lamp V.A.G 1527 d byV ua
ran
◆ Adapter set V.A.G 1594 oris
e
tee
◆ Current flow diagram au
th or
a
ss c

ce
e

Check conditions
nl

pt
du

an
itte

y li
erm

• Throttle valve potentiometer (G69) OK.

ab
ility
• Fuse 15 and 21 OK.
ot p

wit
, is n

h re
Work sequence
hole

spec
es, in part or in w

Note:

t to the co
If the final control diagnosis is to be repeated without the engine being started in between time, switch ignition
off for approx. 20 seconds.

rrectness of i
l purpos

- Connect fault reader V.A.G 1551 (V.A.G 1552) and select engine electronics control unit (address word 01);
carry out selection with ignition switched on. => Page 2
nform
ercia

-> Indicated on display:

m

at
om

Rapid data transfer HELP

ion

Select function XX
c

in t
or

his
ate

- Operate fault reader taking into account the information on the display:
do
priv

- Input 03 for "Final control diagnosis" function.

um
for

en
ng

t.
yi Co
-> Indicated on display: ht. Cop py
rig
rig ht
Rapid data transfer Q py by
Vo
03 Final control diagnosis co lksw
by
cted agen
Prote AG.

Activate throttle valve positioner (V60):

- Confirm input with Q button.

-> Indicated on display:

Final control diagnosis
Throttle valve positioner-V60

The throttle valve positioner plunger must move in and out until switching to the next final control by pressing
the ⇒key.

If the throttle valve positioner does not move:

- Check activation =>Page 37

Activate intake manifold preheating relay (J81):

8 01 - Self-diagnosis
 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995
- Press ⇒key.

-> Indicated on display:

Final control diagnosis
Intake air preheating relay-J81

The intake air preheating relay (on relay plate in footwell driver's side) must click until switching to the next
final control by pressing the ⇒key.
AG. Volkswagen AG d
agen oes
ksw
If the relay does not click: byV
ol not
gu
ara
ed
ris nte
o
- Check intake air preheating relay:auth eo
ra
ss c

ce
le
=> Current flow diagrams, Electrical fault finding and Fitting locations
un

pt
an
d
itte

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Activate solenoid valve 1 for activated charcoal filter (N80):
erm

ab
ility
ot p

wit
- Press ⇒ button.
is n

h re
ole,

spec
-> Indicated on display:
urposes, in part or in wh

t to the co
Final control diagnosis
Activ. charcoal filter solenoid valve
1 -N80

rrectne
The solenoid valve (on air cleaner) must click until the final control diagnosis is ended by pressing the ⇒key.

ss
If the solenoid valve clicks:

o
cial p

f inform
- Press ⇒ key to end the final control diagnosis.
mer

atio
m

-> Indicated on display:

o

n
c

i
or

n thi
e

Function is not recognized or cannot

t

sd
a

⇒
iv

o
r

be carried out at the moment!

p

cum
r
fo

en
ng

t.
yi
- Press ⇒ key again.
Co
Cop py
ht. rig
rig ht
Note:
py by
co Vo
by lksw
cted agen
Prote AG.
After completion of the final control diagnosis input 06 for "End output" function and confirm with Q.

If the solenoid valve does not click:

- -> Pull connector off valve and connect diode test lamp V.A.G 1527 with aux. cables from V.A.G 1594 to
disconnected connector.
The LED must flash

LED flashes:

1.8 - Final control diagnosis 9

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995
- Switch off ignition
- Renew solenoid valve.

LED does not flash:

- Switch off ignition

- -> Connect test box V.A.G 1598/18 to control unit wiring loom.

- -> Check wire between test box socket 3+2 pin connector contact swage 1 according to current
n AG. Volkswagen AG do
es n flow diagram for
open circuit. byV
olk ot g
ua
Wire resistance: max. 1.5 ω ir se
d ran
tee
- Also check wire for short to battery positive and uearth.
tho
or
Specification: ∞ω ss
a ac
- Check wire between 2 pin connector contact 2 and relay plate according to current flow diagram for open
ce
le
un

pt

circuit.
an
d
itte

Wire resistance: max. 1.5 ω

y li
erm

ab
ility
ot p

If no wiring fault is detected:

wit
is n

h re
ole,

- Renew Mono Motronic control unit (J257)

spec
urposes, in part or in wh

=>Page 19 , item 2 .
t to the co

1.9 - Coding control unit

rrectness

Special tools, testers, measuring instruments and auxiliary items required

o
cial p

f inform
mer

◆ Fault reader V.A.G 1551 or vehicle system tester V.A.G 1552 with cable V.A.G 1551/3
atio

◆ Test box V.A.G 1598/18

om

◆ Hand multimeter V.A.G 1526 or multimeter V.A.G 1715

n
c

i
or

◆ Adapter set V.A.G 1594

thi
te

sd
a

◆ Current flow diagram

iv

o
pr

cum
r
fo

en
ng

t.
yi Co
Cop py
t. rig
gh ht
pyri by
Vo
co lksw
by
cted agen
Prote AG.
10 01 - Self-diagnosis
 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995
Test conditions

• No faults stored in fault memory

=> Page 3 , interrogating fault memory

Work sequence

- Connect fault reader V.A.G 1551 (V.A.G 1552) and select engine electronics control unit with the "Address
word" 01. When doing this the ignition must be switched on.
(Connecting fault reader and selecting engine electronics control unit => Page 2 .)

-> The fault reader display will show the control unit identification.
1 HO 907 311P 1.8 ltr. R4 MONO
1.2.3 DGC n AG. Volkswagen AG do
Coding 01 lkswage es n
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byV ua
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ir se
◆ Coding 01 =Manual gearboxutho tee
or
◆ Coding 02 =Automatic gearbox
ss
a ac

ce
e
nl

pt
If the display does not indicate as described:
du

an
itte

y li
erm

ab
- Switch off ignition.

ility
ot p

wit
, is n

h re
hole

spec
es, in part or in w

t to the co
rrectness of i
l purpos

nf
ercia

orm
m

atio
om

n in
or c

- -> Connect test box V.A.G 1598/18 to control unit wiring loom.
thi
te

sd

- Switch ignition on.

iva

o
r

- Check voltage with multimeter and aux. cables from V.A.G 1594 between test box sockets 1 and 40.
rp

cu
o

Specification:
f

en
ng

t.
yi
Vehicles with automatic gearbox: min. 11 V
Co
op py
Vehicles with manual gearbox: 0 V t. C rig
gh ht
pyri by
Vo
co lksw
by
If the specification is not obtained: Prote
cted AG.
agen

- Check wiring according to current flow diagram.

1.10 - Erasing values learnt by engine electronics control unit

Special tools, testers and auxiliary items

◆ Fault reader V.A.G 1551 or vehicle system tester V.A.G 1552 with cable V.A.G 1551/3

Work sequence

- Connect fault reader V.A.G 1551 (V.A.G 1552) and select engine electronics control unit (address word 01);
carry out selection with ignition switched on. => Page 2

-> Indicated on display:

1.9 - Coding control unit 11

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995

Rapid data transfer HELP

Select function XX

- Operate fault reader taking into account the information on the display:
- Input 10 for "Adaption" function and confirm with Q.

-> Indicated on display:

Adaption
Feed in channel number XX

- Input 00 for channel number 0 and confirm with Q.

-> Indicated on display:

Adaption Q
Erase learnt values?

- Confirm entry by pressing Qkey.

-> Indicated on display:

Adaption
Learnt values have been erased

- Conclude adaption by pressing ⇒ key.

. Volkswagen AG
gen AG does
swa
1.11 - Read measured value block and basic bsettings yV
olk not
gu
d ara
ise nte
or eo
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aut ra
The measured values in the functions read measured
ss value block and basic setting are describedcduring the

ce
le

individual component test. This table serves only as an overview.

un

pt
an
d
itte

y li
Note:
erm

ab
ility
ot p

To change to another display group proceed as follows:

wit
is n

h re
ole,

spec
Display group V.A.G 1551 V.A.G 1552
urposes, in part or in wh

t to the co
Higher Press key 3 Press ↑key
Lower Press key 1 Press ↓key
rrectne

1.12 - Display group overview

ss o
cial p

f inform

Display group 00 (decimal displayed value)

mer

atio

▪ Engine not running, ignition switched on

om

n
c

Display zones
i
or

n thi
e

1 2 3 4 5 6 7 8 9 10 Adaption value for solenoid valve 1 for activated charcoal filter

t

sd
iva

o
pr

Battery voltage
um
r
fo

en
ng

Adaption value for idling speed stabilization

t.
yi Co
op py
Adaption value for basic air requirement
. C rig
ht ht
rig by
py
Adaption value for mixture correction co Vo
by lksw
cted agen
Adaption value for injector
Prote AG.

Idling switch
Throttle valve potentiometer -path 1 and 2
Throttle valve potentiometer -path 1

12 01 - Self-diagnosis
 Caddy 1996 AG.,VPolo
olkswagClassic
en AG 1996 ➤
agen does
Mono Motronic injection and ignition
Volksw system - Edition 11.1995
not
g y ua
db ran
ise
Display group 00 (decimal displayed value) tho
r tee
or
au ac
Coolant temperature ss

ce
e
nl

pt
du

an
Display group 00 (decimal displayed value)

itte

y li
erm

ab
▪ Engine idling

ility
ot p
Display zones

wit
, is n

h re
1 2 3 4 5 6 7 8 9 10 Adaption value for solenoid valve 1 for activated charcoal filter

hole

spec
Battery voltage

es, in part or in w

t to the co
Adaption value for idling speed stabilization
Adaption value for basic air requirement
Adaption value for mixture correction

rrectness of i
Lambda control
Intake air temperature l purpos
Engine speed

nf
ercia

or
Throttle valve potentiometer -path 1

m
m

atio
m

Coolant temperature
o

n in
or c

thi
te

Display zones

sd
iva

o
r
rp

cu
1 2 3 4
o

m
f

en
ng

Display group 01 -Idling test-

t.
yi Co
op py
Display 0...xxxx rpm -xx.x...xxx.x °C 0.x.x... 1.xx xxxxxxxx
t. C rig
gh ht
yri by
Indicated Engine speed Coolant temperature Lambda correction factor Operating conditions2)
cop Vo
by lksw
cted agen
Prote AG.

Display group 02 -Injection period, intake air temperature-

Display 0...xxxx rpm 0.0...xxx.x ms 0.0...xx.x V -xx.x...xxx.x °C
Indicated Engine speed Injection period Battery voltage Intake air temperature

Display group 03 -Engine load condition-

Display 0...xxxx rpm 0...xxx % -xx.x° before TDC...xx.x° after 0...xxx <°
TDC
Indicated Engine speed Engine load signal Throttle valve angle (calcula‐ Ignition timing figure (calculated
ted figure, dependent on figure, dependent on the ignition
throttle valve potentiometer) timing adjustment)

1) Relevance of figures in 8 digit number block => Page 14 .

2) This value must not be used to check or adjust the ignition timing.

Display zones
1 2 3 4
Display group 04 -Operating conditions-
Display 0...xxxx rpm 0...xxx % 0,>4>,>7 xxxxxxxx
Indicated Engine speed Engine load signal Speed Operating condition1)

Display group 05 -Mixture control-

Display 0...xxxx rpm 0...xxx % 0.xx...1.xx -xx.x...xx.x %
Indicated Engine speed Duty cycle from activated char‐ Lambda correction factor Mixture correction factor
coal filter solenoid valve 1

1) Relevance of figures in 8 digit number block => Page 14 .

1.12 - Display group overview 13

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995
Significance of figures in 8 digit number block

Significance when displayed digit = 1

x x x x x x x x Display group 01 Display group 04
1 --- ---
1 Idling switch closed ---
1 --- ---
1 Air conditioner compressor
n AG. Vo lkswagswitched
en AG d
oes on Acceleration or full load enrichment
wage
1 Volks
Air conditioner switched on
not
g Full load recognised
y ua
db ran
se
1 ho
ri --- tee Part load recognised
ut or
1 ss a Tightening torque reduction1) Idling
ac switch closed

ce
e

1 Driving stage engaged Fuel cut-off active

nl

pt
du

an
itte

y li
erm

1) Display must always show 1.

ab
ility
ot p

wit
, is n

h re
hole

spec
es, in part or in w

t to the co
rrectness of i
l purpos

nform
mercia

at
om

ion
c

in t
or

his
ate

do
priv

cum
for

en
ng

t.
yi Co
Cop py
ht. rig
rig ht
py by
co Vo
by lksw
cted agen
Prote AG.

14 01 - Self-diagnosis
 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995

24 - Mixture preparation, Injection

1 - Mono-Motronic injection and ignition system

1.1 - Mono-Motronic injection and ignition system

AG. Volkswagen AG d
agen oes
olksw not
V gu
d by ara
ise nte
or eo
h
aut ra
ss c

ce
le
un

pt
an
d
itte

y li
erm

ab
ility
ot p

wit
is n

h re
ole,

spec
urposes, in part or in wh

t to the co
rrectness o
cial p

f inform
mer

atio
om

n
c

i
or

n thi
te

sd
iva

o
pr

cum
r
fo

en
ng

t.
yi Co
Cop py
t. rig
gh ht
pyri by
Vo
o
by c lksw
cted agen
Prote AG.

1.2 - Fitting locations overview

1 4 pin connector
◆ For Lambda probe (G39)
◆ On engine mount - Right
2 Connector
◆ For injector and intake air temperature sender
3 Fuel pressure regulator
4 Injector (N30) with intake air temperature sender (G42)
5 Throttle valve positioner (V60) with idling switch (F60)

1.1 - Mono-Motronic injection and ignition system 15

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995
6 Throttle valve potentiometer (G69)

AG. Volkswagen AG d
agen oes
olksw not
y V gu
d b ara
rise nte
tho eo
au ra
ss c
ce
le
un

pt
an
d
itte

y li
rm

ab
pe

ility
ot

wit
, is n

h re
hole

spec
es, in part or in w

t to the co

7 Temperature regulator
rrectness of i

◆ For intake air preheating

l purpos

8 Injection unit
9 Connector for intake manifold preheating
nform
ercia

10 Ignition transformer (N152)

◆ With ignition transformer output stage (N157)
m

a
com

◆ =>Page 65
ion in

11 Intake manifold preheating relay (J81)

r
te o

thi

◆ Location: On relay plate in driver's side footwell

s
iva

do
r
rp

12 Mono Motronic injection and ignition system control unit (J257)

um
fo

en
ng

t.
yi Co
Cop py
t. rig
gh ht
pyri by
Vo
co lksw
by
cted agen
Prote AG.

16 24 - Mixture preparation, Injection

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995

n AG. Volkswagen AG do
lkswage es n
o ot g
byV ua
d ran
ir se tee
tho
u or
a ac
ss

ce
e
nl

pt
du

an
itte

y li
erm

ab
ility
ot p

wit
, is n

h re
hole

spec
es, in part or in w

t to the co
rrectness of i
l purpos

nf
ercia

orm
m

13 Distributor with Hall sender (G40)

atio
om

◆ =>Page 66
n in
or c

thi

14 Coolant temperature sender (G62)

te

sd
iva

◆ with coolant temperature indicator sender (G2)

o
r
rp

cu
o

15 Earth connection
f

en
ng

t.
yi Co
16 Vacuum unit t. Cop py
rig
◆ For intake air preheating
gh ht
pyri by
Vo
o
17 Activated charcoal filter solenoid valve 1 (N80)
c by lksw
cted agen
Prote AG.

=> Repair group 20, removing and installing parts of the fuel supply system, removing and installing parts of
the activated charcoal filter system

18 Air cleaner

1.3 - Servicing injection part

Servicing ignition part

1.2 - Fitting locations overview 17

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995
=> Repair group 28 agen
AG. Volkswagen AG d
Notes: w es n o
olks ot g
yV
◆ The control unit for the fuel injection and ignition system is equipped
ed b with a fault memory. Before carrying
ua
ran
out repairs, adjustment work and fault finding the fault memory oris must be interrogated and the vacuum con‐ tee
th or
nections checked (outside air). ss
au ac
◆ Components marked with * are checked via the self diagnosis.

ce
le
un
=> Page 3 , interrogating fault memory

pt
an
d
◆ Components marked with ** are checked via the final control control diagnosis => Page 8 .

itte

y li
rm
◆ Always renew spring-type hose clips with screw-type hose clips.

ab
pe

ility
◆ For trouble-free operation of the electrical components a voltage of at least 11.5 V is necessary.

ot

wit
◆ If the engine starts, runs for a short period and then stops, after fault finding, repairs or component tests,

, is n

h re
then the fault may lie with the immobilizer which is blocking the engine control unit. The fault memory must

hole

spec
be interrogated and if necessary the control unit matched => Page 58 .

es, in part or in w

t to the co
◆ During some checks it can happen that the control unit will recognise and store a fault. Therefore after
completing all checks and repairs the fault memory must be interrogated and if necessary erased.
=> Page 3 , interrogating fault memory

rrectness of i
◆ Do not use sealants containing silicone. Particles of silicone drawn into the engine, will not be burnt in the
engine and damage the Lambda probe.
l purpos

Safety precautions =>Page 31

nform
ercia

Rules for cleanliness => Page 31

Technical data => Page 32
m

a
com

t
Checking intake air system for leaks (unmetered air) => Page 61 .

ion in
r
te o

thi
s
iva

do
r
rp

cum
fo

en
ng

t.
yi Co
Cop py
ht. rig
rig ht
py by
co Vo
by lksw
cted agen
Prote AG.

18 24 - Mixture preparation, Injection

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995
I => Page 19

II => Page 22

III => Page 24 AG. Volkswagen AG d

agen oes
olksw not
y V gu
d b ara
rise nte
tho eo
au ra
ss c

ce
le
un

pt
an
d
itte

y li
rm

ab
pe

ility
ot

wit
, is n

h re
hole

spec
es, in part or in w

t to the co
rrectness of i
l purpos

nform
mercia

a
com

tion in
r
te o

thi
s
iva

do
r
rp

cum
fo

en
ng

t.
yi Co
Cop py
t. rig
gh ht
pyri by
Vo
co lksw
by
cted agen
Prote AG.

Part I

1 Connector
◆ Only disconnect or connect with ignition switched off
◆ Unlatch to disconnect
2 Mono Motronic control unit (J257)*
◆ For injection system, Lambda regulation, activated charcoal filter solenoid valve, speed governing via
fuel pump relay, intake air preheating control, ignition and self diagnosis
◆ Location: in plenum chamber, left
◆ On replacement, the control unit must be matched to the electronic immobilizer => Page 58

1.3 - Servicing injection part 19

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995

n AG. Volkswagen AG do
lkswage es n
o ot g
byV ua
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ir se tee
tho
u or
3 10 Nm ss
a ac
4 Retainer
ce
le
un

pt

◆ For control unit

an
d
itte

y li
rm

5 Connector
ab
pe

ility

◆ 4 pin
ot

wit
, is n

6 Coolant temperature sender (G62)*

h re
hole

◆ With coolant temperature gauge sender (G2)

spec

◆ If necessary before removing, release pressure from cooling system

es, in part or in w

t to the co

◆ Checking =>Page 45
◆ Resistance graph
=>Page 31 , Fig. 1
rrectness of i

7 O ring
◆ Renew if damaged
l purpos

8 Retaining clip
9 Connection
nform
mercia

a
com

tion in
r
te o

thi
s
iva

do
r
rp

cum
fo

en
ng

t.
yi Co
Cop py
t. rig
gh ht
pyri by
Vo
co lksw
by
cted agen
Prote AG.
20 24 - Mixture preparation, Injection
 . Volkswagen AG
n AGCaddy
swage 1996do,esPolo Classic 1996 ➤
lk not
Mono Motronic dinjection
by
Vo and ignition system g-u Edition 11.1995
ara
e nte
oris eo
th
au ra
ss c

ce
e
nl

pt
du

an
itte

y li
erm

ab
ility
ot p

wit
, is n

h re
hole

spec
es, in part or in w

t to the co
rrectness of i
l purpos

nf
ercia

orm
m

atio
om

n in
or c

thi
te

sd
iva

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cu
o

m
f

en
ng

t.
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Cop py
t. rig
gh ht
pyri by
Vo
co lksw
by
cted agen
Prote AG.

10 Lambda probe (G39)*, 50 Nm

◆ Location: in exhaust manifold
◆ Grease only the threads with "G5"; "G5" must not get into the slots on the probe body
◆ Checking Lambda probe and Lambda control
=> Page 33
◆ Checking probe heating voltage supply => Page 35
◆ Check probe heating for continuity
11 Connector
◆ 4 pin
◆ For Lambda probe and probe heating

1.3 - Servicing injection part 21

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995

AG. Volkswagen AG d
agen oes
olksw not
byV gu
ara
ed
ris nte
ho eo
aut ra
ss c
ce
e
nl

pt
du

an
itte

y li
erm

ab
ility
ot p

wit
, is n

h re
hole

spec
es, in part or in w

t to the co
rrectness of i
l purpos

Part II
nform
ercia

1 Intake hose
m

at

◆ To air cleaner
om

ion
c

2 10 Nm
in t
or

his
te

3 To vacuum unit on air cleaner

a

do
priv

4 Retainer
um
for

en
g

5 Seal
n

t.
yi Co
op py
◆ Renew if damaged
. C rig
ht ht
rig
6 Temperature regulator
py by
co Vo
by lksw
◆ For intake air preheating
cted agen
Prote AG.
◆ Checking intake air preheating =>Page 62
7 Intake elbow
8 Oil seal
◆ Renew if damaged

22 24 - Mixture preparation, Injection

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995

n AG. Volkswagen AG do
lkswage es n
o ot g
byV ua
d ran
ir se tee
tho
u or
a ac
ss

ce
e
nl

pt
du

an
itte

y li
erm

ab
ility
ot p

wit
, is n

h re
hole

spec
es, in part or in w

t to the co
rrectness of i
l purpos

nf
ercia

orm
m

atio
om

n in
or c

thi
e

9 To activated charcoal filter solenoid valve 1 (N80)

t

sd
iva

o
r

◆ => Page 17 , item 17

rp

cu
o

◆ Activated charcoal filter system m

f

en
ng

t.
yi Co
Cop py
=> Repair group 20, removing and installing parts of the fuel supply system, removing and installing parts of
t. rig
gh ht
yri
the activated charcoal filter system p by
co Vo
by lksw
cted agen
Prote AG.
10 Connector
11 Return pipe
12 Supply pipe
13 Injection unit
◆ Servicing => Page 26

1.3 - Servicing injection part 23

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995

AG. Volkswagen AG d
agen oes
olksw not
y V gu
d b ara
rise nte
tho eo
au ra
ss c

ce
le
un

pt
an
d
itte

y li
erm

ab
ility
ot p

wit
is n

h re
ole,

spec
urposes, in part or in wh

t to the co
rrectness o
cial p

f inform
mer

atio
om

n
c

i
or

n thi
te

sd
iva

o
pr

Part III
um
r
fo

en
ng

t.
yi Co
1 Bracket t. Cop py
rig
◆ For warm air collector plate
gh ht
pyri by
Vo
o
2 25 Nm
c by lksw
cted agen
Prote AG.
3 20 Nm
4 Warm air collector plate
5 Flange
◆ Check for cracks and distortion
6 13 Nm
◆ Secure bolt under throttle valve lever with a locking plate.
7 Support
◆ For intake manifold

24 24 - Mixture preparation, Injection

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995

AG. Volkswagen AG d
agen oes
olksw not
V gu
d by ara
ise nte
or eo
h
aut ra
ss c

ce
le
un

pt
an
d
itte

y li
erm

ab
ility
ot p

wit
is n

h re
ole,

spec
urposes, in part or in wh

t to the co
rrectness o
cial p

f inform
mer

atio
om

n
c

i
or

n thi
e

8 To coolant pipe
t

sd
iva

9 Vacuum connection
pr

cum
r
fo

◆ To brake servo
en
ng

t.
yi Co
10 O ring Cop py
t. rig
◆ Renew if damaged
gh ht
pyri by
Vo
o
11 Seal
by c lksw
cted agen
Prote AG.
◆ Renew
12 Intake air preheater (N51)
◆ Test prerequisites: engine cold
◆ Resistance between plug and earth (-): 0.25...0.50 ω
◆ Checking activation
=> Page 8 , Final control diagnosis
13 10 Nm
14 Oil seal
15 Intake manifold

1.3 - Servicing injection part 25

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995

1.4 - Servicing injection unit

AG. Volkswagen AG d
agen oes
olksw not
byV gu
ara
ed
ris nte
ho eo
aut ra
ss c

ce
le
un

pt
an
d
itte

y li
erm

ab
ility
ot p

wit
is n

h re
ole,

spec
urposes, in part or in wh

t to the co
rrectness o
cial p

f inform
mer

atio
om

n
c

i
or

n thi
te

sd
iva

o
pr

cum
r
fo

en
ng

t.
yi Co
Cop py
ht. rig
rig ht
py by
co Vo
by lksw
cted agen
Prote AG.

Servicing upper part

1 5 Nm
◆ Install with D6
2 Protective cap
◆ Only on replacement part for transportation protection of intake air temperature sender, must be removed
after installation
3 Retainer for injector with intake air temperature sender (G42)*
◆ Checking intake air temperature sender =>Page 48
◆ Resistance graph
=>Page 31 , Fig. 1
4 O ring
◆ Renew

26 24 - Mixture preparation, Injection

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995

AG. Volkswagen AG d
agen oes
olksw not
byV gu
ara
ed
ris nte
ho eo
aut ra
ss c

ce
le
un

pt
an
d
itte

y li
rm

ab
pe

ility
ot

wit
, is n

h re
hole

spec
es, in part or in w

t to the co
rrectness of i
l purpos

nform
mercia

a
com

tion in
r
te o

thi
s
iva

do
r
rp

cum
fo

5 Injector (N30)
en
ng

t.
yi Co
op
◆ Checking =>Page 50 C py
ht. rig
6 6 Nm
rig ht
py by
co Vo
◆ Install with D6
by lksw
cted agen
Prote AG.
7 Injection unit upper part
◆ Note fitting position
8 Seal
◆ Note fitting position
◆ Renew if damaged
9 Connection
10 Seal
◆ Renew
11 Fuel pressure regulator
◆ Checking fuel pressure regulator and holding pressure => Page 59
12 Plug
◆ Release retainers to remove

1.4 - Servicing injection unit 27

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995

AG. Volkswagen AG d
agen oes
olksw not
y V gu
d b ara
rise nte
tho eo
au ra
ss c ce
le
un

pt
Servicing lower part
an
d
itte

y li
rm

ab

1 Throttle valve positioner (V60)*/**

pe

ility
ot

◆ With idling switch (F60)*

wit
, is n

◆ Checking =>Page 37
h re
hole

◆ When installing ensure that idling switch can only be operated via switch plastic plate with stop screw.
spec

If necessary loosen bracket -4- and align.

es, in part or in w

t to the co

◆ Check idling after renewing the idling switch

=>Page 38
◆ With throttle valve positioner sender (G127)*;
rrectness of i

Checking sender =>Page 42

2 6 Nm
l purpos

nform
mercia

a
com

tion in
r
te o

thi
s
iva

do
r
rp

cum
fo

en
ng

t.
yi Co
Cop py
t. rig
gh ht
pyri by
Vo
co lksw
by
cted agen
Prote AG.

28 24 - Mixture preparation, Injection

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995

AG. Volkswagen AG d
agen oes
olksw not
V gu
d by ara
ise nte
or eo
h
aut ra
ss c

ce
le
un

pt
an
d
itte

y li
rm

ab
pe

ility
ot

wit
, is n

h re
hole

spec
es, in part or in w

t to the co
rrectness of i
l purpos

nform
mercia

3 Idling switch (F60)

com

tion in

◆ Checking and adjusting

r
te o

thi

=>Page 38
s
iva

◆ Renewing: Renew throttle valve positioner

do
r
rp

cum

4 Support bracket
fo

en
ng

t.
yi
◆ For accelerator cable
Co
op py
◆ Adjusting accelerator cable t. C rig
gh ht
pyri by
Vo
o
by c lksw
=> Repair group 20; Removing and installing parts of the fuel supply system; Adjusting accelerator cable Re‐
Prote
cted agen
moving and installing parts of the fuel supply system Adjusting accelerator cable
AG.

5 Injection unit lower part

6 Limiting screw
◆ The screw is sealed at the factory and must not be moved!
7 3 Nm
8 Retainer

1.4 - Servicing injection unit 29

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995

AG. Volkswagen AG d
agen oes
olksw not
V gu
d by ara
ise nte
or eo
h
aut ra
ss c

ce
e
nl

pt
du

an
itte

y li
erm

ab
ility
ot p

wit
, is n

h re
hole

spec
es, in part or in w

t to the co
rrectness of i
l purpos

nf
ercia

o
9 Vacuum connection

rm
m

atio
◆ For activated charcoal filter system
om

n in
or c

=> Repair Group 20; Removing and installing parts of fuel supply system; Removing and installing parts of thi
te

sd
a

activated charcoal filter system Removing and installing parts of fuel supply system Removing and installing
iv

o
r
rp

cu

parts of activated charcoal filter system

o

m
f

en
ng

t.
yi Co
op
10 Vacuum connection C py
t. rig
gh
◆ For intake air preheating
ht
pyri by
Vo
o
by c
11 O ring
lksw
cted agen
Prote AG.
◆ Renew if damaged
12 Throttle valve potentiometer (G69)*
◆ Checking =>Page 43
◆ Must not be adjusted
◆ If defective: renew injection unit lower part
◆ Contacts gold plated
◆ Only automatic gearbox:
After replacing the injection part the automatic gearbox control unit (J217) and the throttle valve poten‐
tiometer (G69) must be matched to one another
=> Page 56
◆ Manual gearbox: 5 pin

30 24 - Mixture preparation, Injection

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995
◆ Automatic gearbox: 7 pin

AG. Volkswagen AG d
agen oes
olksw not
y V gu
d b ara
rise nte
tho eo
au ra
ss c

ce
e
nl

pt
du

an
itte

y li
erm

ab
ility
ot p

wit
, is n

h re
hole

spec
es, in part or in w

t to the co
-> Fig. 1 Resistance graph

rrectness of i
The diagram is valid for coolant temperature sender (G62) and intake air sender (G42).
l purpos

Scale A shows resistance values for temperature range 0...50 °C and scale B the values for temperature range
50...100 °C.

nf
ercia

orm
Examples:
m

atio
om

n in
c

◆ 30 °C corresponds to a resistance from 1500...2000 ω

or

thi
e

◆ 80 °C corresponds to a resistance from 275...375 ω

t

sd
iva

o
r
rp

cu
o

m
f

en
ng

t.
yi Co
1.5 - Safety precautions Cop py
t. rig
gh ht
pyri by
Vo
co lksw
by
cted agen
Prote AG.
Warning!
Fuel system is under pressure! Before opening the system place a cloth around the connection. Then release
pressure by carefully loosening the connection.

To prevent injuries to persons and/or damage to the fuel injection and ignition system, the following must be
noted:

◆ Do not touch or disconnect ignition wiring when the engine is running or being turned at starter speed.
◆ The ignition must be switched off before connecting or disconnecting injection or ignition system wiring or
tester cables.
◆ If the engine is to be turned at starter speed, without starting, e.g. when checking compressions, pull plug
off Hall sender (distributor).

1.6 - Rules for cleanliness

When working on the fuel supply/injection system, pay careful attention to the following "5 rules":

◆ Thoroughly clean all unions and the adjacent areas before disconnecting.
◆ Place parts that have been removed on a clean surface and cover. Do not use fluffy cloths!
◆ Carefully cover opened components or seal, if the repair cannot be carried out immediately.
◆ Only install clean components:
Only unpack replacement parts immediately prior to installation.
Do not use parts that have been stored loose (e.g. in tool boxes etc.).
◆ When the system is open:
Do not work with compressed air if this can be avoided.

1.4 - Servicing injection unit 31

 AG. Volkswagen A
Caddy 1996 , Polo Classic 1996 o➤ agen G do
es n
ksw
V l ot g
Mono Motronic injection and eignition
db
y system - Edition 11.1995 ua
ra
ris nte
tho eo
Do not move vehicle unless absolutely
au necessary. ra
c
ss

ce
e
nl

pt
du

an
itte

y li
1.7 - Technical data

erm

ab
ility
ot p

wit
, is n
Engine code 1F ADZ

h re
hole
Idling test2)

spec
Idling speed rpm 700...10001) 775...9751)
es, in part or in w

t to the co
Mono Motronic control unit
Part No. Parts microfiche Parts microfiche

rrectness of i
Governed speed rpm approx. 6300 approx. 6300
l purpos

1) Up-to-date specifications:
=> Exhaust emissions test binder

nf
ercia

orm
m

2) Idling speed is not adjustable, observe test conditions => Page 32

atio
om

n in
or c

thi
te

sd
iva

1.8 - Idling speed check

o
r
rp

cu
o

m
f

en
ng

t.
yi Co
op py
Notes: t. C rig
gh ht
pyri by
Vo
co
◆ Idling speed not adjustable.
by lksw
cted agen
Prote
◆ CO content regulated by Lambda regulation. Faults in Lambda control are detected in self-diagnosis and
AG.

stored in fault memory.

Special tools, testers and auxiliary items

◆ Ignition tester V.A.G 1767 or V.A.G 1367 with HT pick-up clamp V.A.G 1367/8

Test conditions
• No faults stored in fault memory
=> Page 3 , interrogating fault memory
• Accelerator cable adjustment OK

=> Repair group 20; Removing and installing parts of fuel supply system; Adjusting throttle cable Removing
and installing parts of fuel supply system Adjusting throttle cable
• Exhaust system must be free of leaks
• Engine oil temperature min. 80 °C
• Electrical consumers switched off (radiator fan must not run during the check)
• Air conditioner switched off
• Ignition timing OK., checking
=> Page 69

32 24 - Mixture preparation, Injection

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995
Test sequence
- -> Connect ignition tester V.A.G 1767 or ignition tester V.A.G 1367 with HT pick-up clamp V.A.G 1367/8.
- Start engine and run at idling speed.

- Check idling speed.

Specification:
1F: 700...1000 rpm1)
ADZ: 775...975 rpm1)

1) Up-to-date specifications:
=> Exhaust emissions test binder
If the specification is not attained:
- Check throttle valve positioner => Page 37

G. Volkswagen AG d
1.9 - Checking Lambda probe and Lambdaolcontrol
ksw
agen
A
oes
not
yV gu
db ara
rise nte
tho eo
Special tools, testers and auxiliary items s au ra
c
s

ce
e

◆ Fault reader V.A.G 1551 or vehicle system tester V.A.G 1552 with cable V.A.G 1551/3
nl

pt
du

an
◆ Test box V.A.G 1598/18
itte

y li
◆ Hand multimeter V.A.G 1526 or multimeter V.A.G 1715
erm

ab
◆ Adapter set V.A.G 1594

ility
ot p

◆ Current flow diagram

wit
, is n

h re
hole

Check conditions

spec
es, in part or in w

t to the co
• Coolant temperature at least 85 °C
• Exhaust system between catalyst and cylinder head free of leaks

rrectness of i
Functional check of Lambda probe
l purpos

- Connect fault reader V.A.G 1551 (V.A.G 1552) and select engine electronics control unit (address word 01);
carry out selection at idling.
=> Page 2

nf
ercia

orm
m

-> Indicated on display: atio

om

n in
or c

Rapid data transfer HELP

thi
e

Select function XX
t

sd
iva

o
r
rp

cu

- Input 08 for "Read measured value block" function and confirm with Q.
o

m
f

en
ng

t.
yi Co
op
-> Indicated on display: C py
ht. rig
rig ht
Read measured value block HELP py by
co Vo
Input display group number XX by lksw
cted agen
Prote AG.

- Input 00 for "Display group number" and confirm with Q.

-> Indicated on display:

(1...10 = Display zones)
Read measured value block 0
1 2 3 4 5 6
7 8 9 10

- Note reading in display zone 1 (coolant temperature),

Specification: max. 22 (corresponds to at least 85 °C)
if necessary, run engine until temperature reached.
- Note reading in display zone 5 (Lambda reading).
Specification: varying between 106...150

1.8 - Idling speed check 33

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995
- Note reading in display zone 6 (altitude correction).

Altitude of workshop Specification

0m 241...255 or 0...30
250 m 235...255 or 2...24 agen
AG. Volkswagen AG d
oes
ksw not
500 m 228...255 by or 0...17
V ol
gu
ara
ed
750 m 222...255
horis or 0...11 nte
eo
ut ra
1000 m ss 215...255
a or 0...4 c

ce
e

1250 m 209...254
nl

pt
du

an
1500 m 202...247
itte

y li
erm

ab
1750 m 195...240

ility
ot p

2000 m 188...233

wit
, is n

h re
2250 m 182...227
hole

spec
2750 m 168...213
es, in part or in w

t to the co
3000 m 162...207

If specification attained:

rrectness of i
l purpos

- Press ⇒ key.
- Input 06 for "End output" and confirm with Q.

nf
ercia

If specification not attained or exceeded:

orm
m

atio
m

- Check Lambda probe heating => Page 35 .

o

n in
or c

- Check intake air system for leaks (unmetered air). To do this, leave fault reader in this setting and allow

thi
e

engine to continue running

t

sd
iva

o
=> Page 61
r
rp

cu
o

m
- Check spark plugs, spark plug connectors, ignition cables.
f

en
ng

t.
yi Co
Cop py
t. rig
gh ht
pyri by
Vo
o
by c lksw
cted agen
Prote AG.

- Check activated charcoal filter solenoid valve -1- for leaks. The valve must always be closed when the
ignition is switched off.
- Check Lambda probe for soot. Renew if necessary.

Checking Lambda probe wiring

- Switch off ignition

- -> Connect test box V.A.G 1598/18 to control unit wiring loom.

34 24 - Mixture preparation, Injection

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995

- -> Separate 4 pin connector to Lambda probe -1-.

- Check wiring between test box and 4 pin connector for open circuit according to current flow diagram.
Contact 3+socket 15
Contact 4+socket 38
Wire resistance: Max. 1.5 ω
- Check wiring at 4 pin connector for short to one another.
Specification: ∞ω

If the specifications are not attained:

- Check wiring according to current flow diagram.

1.10 - Checking Lambda probe heating

Special tools, testers and auxiliary items

◆ Test box V.A.G 1598/18

◆ Hand multimeter V.A.G 1526 or multimeter V.A.G n1715
AG. Volkswagen AG d
◆ Adapter set V.A.G 1594 lkswage oes
not
Vo
◆ Current flow diagram ed by gu
ara
ris nte
tho eo
Check conditions ss
au ra
c
ce
le
un

pt

• Fuse 18 OK.
an
d
itte

• Fuel pump relay OK

y li
rm

ab
pe

ility

Checking voltage supply

ot

wit
, is n

h re
hole

spec
es, in part or in w

t to the co
rrectness of i
l purpos

nform
mercia

a
com

tion in
r
te o

thi

- -> Separate 4 pin connector to Lambda probe.

s
iva

do
r

- Connect multimeter to measure voltage at contacts 1+2 of connector.

rp

cum
fo

- Start engine.
en
ng

t.
Specification: Min. 11 V
yi Co
op py
- Switch off ignition t. C rig
gh ht
pyri by
Vo
co lksw
by
cted agen
Prote AG.

1.9 - Checking Lambda probe and Lambda control 35

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995
If no voltage is present:

- Check wiring to relay plate according to current flow diagram.

1.11 - Checking engine operating mode

Note:

Check establishes whether Mono Motronic control unit (J257) recognises the engine operating modes (idling,
part throttle, acceleration/full throttle enrichment, full throttle and overrun).

Special tools, testers and auxiliary items

AG. Volkswagen AG d
agen o
◆ Fault reader V.A.G 1551 or vehicle system tester V.A.G
Vol
ksw 1552 with cable V.A.Ges1551/3
not
g y ua
db ran
rise tee
Test conditions tho or
au ac
ss
• Coolant temperature at least 80 °C

ce
e
nl

pt
du

an
itte

y li
Test sequence
erm

ab
ility
ot p

- Connect fault reader V.A.G 1551 (V.A.G 1552) and select engine electronics control unit (address word 01);

wit
, is n

carry out selection at idling.

h re
hole

=> Page 2

spec
es, in part or in w

t to the co
-> Indicated on display:
Rapid data transfer HELP
Select function XX

rrectness of i
- Input 08 for "Read measured value block" function and confirm with Q.
l purpos

-> Indicated on display:

nf
ercia

o
Read measured value block HELP

rm
m

Input display group number XX

atio
om

n in
or c

- Enter 04 for "Display group number" and confirm with Q. thi

te

sd
iva

o
r

-> Indicated on display:

rp

cu
o

m
f

(1...4 = Display zones)

en
ng

t.
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Read measured value block 4 Cop py
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cted
- Observe display zone 4 -8 digit number block-:
agen
Prote AG.

Display in operating mode

◆ Idling:

2nd position from right must display 1

Display: 00000010

◆ Part throttle:

- Rev up evenly.

3rd position from right must display 1

Display:: 00000100

◆ Acceleration/full throttle enrichment:

36 24 - Mixture preparation, Injection

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995
. Volkswagen AG
gen AG does
swa
- Quickly open throttleyV
olk valve slightly. not
gu
d b ara
ise nte
r
5th position
ut from right must display 1
ho eo
ra
Display:
ss a 00010100 c

ce
le
un

pt
◆ Full throttle:

an
d
itte

y li
erm

ab
- Floor accelerator pedal and release.

ility
ot p

wit
is n

4th position from left must briefly display 1

h re
ole,

Display: 00011000

spec
urposes, in part or in wh

t to the co
◆ Overrun mode:

- Raise engine speed to above 3000 rpm.

rrectne
- Close throttle abruptly.

s
As long as the engine speed is above 1500 rpm 1st position from left must display 1

s o
Display: 00000011 (briefly)
cial p

f inform
mer

Note:

atio
m

Below 1500 rpm idling speed is again recognised.

o

n
c

i
- Press ⇒ key.
or

n thi
e

- Input 06 for "End output" and confirm with Q.

t

sd
iva

o
pr

cum
r
fo

If the specifications are not attained: en

ng

t.
yi
- Interrogate fault memory. Eliminate faults if necessary => Page 3 .
Co
op py
- Check throttle valve potentiometer
. C rig
ht ht
rig
=> Page 43 . py by
co Vo
- Check idling switch => Page 38 .
by lksw
cted agen
Prote AG.

1.12 - Checking throttle valve positioner

Checking function
Functional check => Page 8 , Final control diagnosis
Checking activation
Special tools, testers and auxiliary items
◆ Hand multimeter V.A.G 1526 or multimeter V.A.G 1715
◆ Diode test lamp V.A.G 1527
◆ Adapter set V.A.G 1594
◆ Current flow diagram

Test conditions
• Fault reader V.A.G 1551 (V.A.G 1552) connected
• Ignition switched off

Test sequence

1.11 - Checking engine operating mode 37

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995
- -> Pull plug -1- off throttle valve positioner (V60) -2- .
- Connect diode test lamp V.A.G 1527 with aux. cables from V.A.G 1594 to contacts 1+6 of the connector.
- Bridge contacts 4+5 with aux. cables from V.A.G 1594.
- Switch on ignition and again perform self-diagnosis until the throttle valve positioner is activated.
LED must light up.
- Slightly open throttle valve and close again.
Both LEDs must light up alternately.

Note:

If the throttle valve is opened too far, separate aux. cables to the contacts 4 + 5, reconnect and repeat check.

- Carry out final control diagnosis up to end.

- Switch off ignition and connect plug.
- Interrogate fault memory=> Page 3 .

Checking resistance

Test conditions

• Ignition switched off.

Test sequence n AG. Volkswagen AG do

lkswage es n
Vo ot g
- Remove air intake eelbow.
d by ua
ran
ir s tee
tho
u or
a ac
ss
ce
e
nl

pt
du

an
itte

y li
erm

ab
ility
ot p

wit
, is n

h re
hole

spec
es, in part or in w

t to the co
rrectness of i

- -> Pull connector -1- off throttle valve positioner -2-.

l purpos

- Check resistance with hand multimeter V.A.G 1526 and aux. cables from V.A.G 1594 at contacts of throttle
valve positioner as follows:
nf
ercia

Specifications:
orm

between contacts 1+6 = 3...200 ω

m

atio
m

between contacts 4+5

o

n in
c

Throttle valve closed = max. 200 ω

or

thi

Throttle valve open =∞ ω

te

sd
iva

o
r
rp

cu

If the specifications between contacts 4+5 are not attained:

o

m
f

en
ng

t.
yi Co
op
- Check idling switch => Page 38 .
C py
t. rig
gh ht
pyri by
Vo
co lksw
by
cted agen
Prote AG.
1.13 - Checking and adjusting idling switch

Special tools, testers and auxiliary items

◆ Fault reader V.A.G 1551 or vehicle system tester V.A.G 1552 with cable V.A.G 1551/3
◆ Hand multimeter V.A.G 1526 or multimeter V.A.G 1715
◆ Test box V.A.G 1598/18
◆ Adapter set V.A.G 1594

38 24 - Mixture preparation, Injection

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995
◆ Current flow diagram

Notes:

◆ The adjustment is only necessary if the throttle valve positioner or the injection unit lower part is replaced.
◆ The idling switch (F60) can only be adjusted if the throttle valve positioner is fully out.

Checking function

- Connect fault reader V.A.G 1551 (V.A.G 1552) and select engine electronics control unit (address word 01);
carry out selection with ignition switched on.
=> Page 2

-> Indicated on display:

Rapid data transfer HELP
Select function XX

- Input 04 for "Initiate basic setting" and confirm with Q.

-> Indicated on display:

Basic setting HELP
Input display group number XX
n AG. Volkswagen AG do
wage es n
- Input 01 for "Display y V group number" and confirm with
olks ot g Q.
ua
d b ran
ir se tee
-> Indicated on uth display:
o
or
(1...4 = Display
ss
a zones) ac
ce
le

System in basic setting 1

un

pt
an

1 2 3 4
d
itte

y li
rm

ab
pe

- Observe 2nd position from left in display zone 4 -8 digit number block-.
ility
ot

Specification: 01000010
wit
, is n

- Open throttle valve slightly. The display at 2nd position from left must jump to 0
h re
hole

Display: 00000010
spec
es, in part or in w

t to the co

If the specifications are not attained:

- Remove air intake elbow.

rrectness of i
l purpos

Display Cause Continuation of

check
Always 1 Short to earth => Page 39
nform
ercia

Always 0 Open circuit or short => Page 40

m

to positive
com

tion in
r
te o

thi

Continuation of check when display = always 1:

s
iva

do
r
rp

cum
fo

en
ng

t.
yi Co
Cop py
t. rig
gh ht
pyri by
Vo
co lksw
by
cted agen
Prote AG.

- -> Pull plug -1- off throttle valve positioner (V60) -2- .

1.13 - Checking and adjusting idling switch 39

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995
Display 0:

- Replace throttle valve positioner (V60).

Display 1:

- Press ⇒ key.
- Input 06 for "End output" and confirm with Q.
- Switch off ignition n AG. Volkswagen AG do
- Pull connector off Mono Motronic l wage
kscontrol unit. es n
Vo ot g
- Check wiring to control unitedat
by 6 pin connector contact 5 for short ua to wire contact 4 and to vehicle earth.
ra
ris nte
tho eo
If no fault in wire is detected:
ss
au ra
c

ce
le
un

- Renew Mono Motronic control unit (J257)

pt
an
d

=>Page 19 , item 2 .
itte

y li
rm

ab
pe

ility
Continuation of check when display = always 0:
ot

wit
, is n

h re
hole

spec
es, in part or in w

t to the co
rrectness of i
l purpos

nform
mercia

a
com

tion in
r
te o

thi

- -> Pull plug -1- off throttle valve positioner (V60) -2- .
s
iva

do

- Bridge connector contacts 4+5 with aux. cables from V.A.G 1594 and observe display.
r
rp

cum
fo

en
ng

t.
Display 1:
yi Co
Cop py
t. rig
gh
- Replace throttle valve positioner (V60).
ht
pyri by
Vo
co lksw
by
cted agen
Display 0:
Prote AG.

- Press ⇒ key.

- Input 06 for "End output" and confirm with Q.

- Switch off ignition
- -> Connect test box V.A.G 1598/18 to control unit wiring loom.

- Check wiring between test box and 6 pin connector for open circuit according to current flow diagram.
Contact 4+socket 20
Contact 5+socket 10

40 24 - Mixture preparation, Injection

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995
Wire resistance: Max. 1.5 ω

If no wiring fault is detected:

- Renew Mono Motronic control unit (J257)

=>Page 19 , item 2 .

Checking adjustment

Note:

The adjustment of the idling switch must be performed in function "04 Basic setting" -positioner fully extended-.
If the basic setting has to be exited for checking the wiring, the system must be brought back to basic setting
with ignition switched on.

-> Indicated on display:

(1...4 = Display zones) AG. Volkswagen AG d
agen oes
olksw not
System in basic setting 1by V gu
ara
1 2 3 4 ise d
r nte
ho eo
aut ra
s c
- Select display groups 00, to do this

ce
le

- On V.A.G 1551 press key 1

un

pt
an
d

- On V.A.G 1552 press key ↓

itte

y li
rm

ab
pe

ility
-> Indicated on display:
ot

wit
(1...10 = Display zones)
, is n

h re
hole

System in basic setting 0

spec
1 2 3 4 5 6
es, in part or in w

7 8 9 10

t to the co
- Observe displayed figure in display zone 2 (throttle valve potentiometer path 1):
Specification: 196...200

rrectness of i
If the specification is not obtained:
l purpos

- Remove air intake elbow.

nform
mercia

a
com

tion in
r
te o

thi
s
iva

do
r
rp

cum
fo

en
ng

t.
yi Co
Cop py
t. rig
gh ht
pyri by
Vo
o
by c lksw
cted agen
Prote AG.

- -> Correct adjustment on the stop screw-arrow-.

Setting value: 198±1

Note:

If during adjustment the throttle valve is opened to gain access to the screw, the control unit will move the
throttle valve positioner back. To move the positioner fully out again, the function basic setting must be selected
again.

If the stop screw adjustment has been corrected, the operation of the idling switch must be checked,=>Page
39

- Press ⇒ button. The throttle valve positioner must move in to its start point.

1.13 - Checking and adjusting idling switch 41

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995
- Input 06 for "End output" and confirm with Q.

If it is not possible to adjust to specification:

- Renew injection unit lower part.

1.14 - Checking sender for throttle valve positioner

Special tools, testers and auxiliary items

◆ Hand multimeter V.A.G 1526 or multimeter V.A.G 1715
◆ Diode test lamp V.A.G 1527
◆ Test box V.A.G 1598/18
◆ Adapter set V.A.G 1594
◆ Current flow diagram

Test conditions
• Fuse 15 OK.

Test sequence
n AG. Volkswagen AG
- Remove air intake elbow. lksw
age does
not
- -> Pull back rubber boot on throttle valve positioner y Vo(V60) plug. gu
d b ara
- Connect diode test lamp V.A.G 1527 with aux. or ise cables from V.A.G 1594 to contacts 2+4. nte
eo
- Initiate final control diagnosis => Page 8 a.uth
ra
When activating the throttle valve positioner
ss
the LED must c
ce
e

flicker.
nl

pt
du

an
itte

y li
erm

ab
ility
ot p

wit
, is n

h re
hole

spec
es, in part or in w

t to the co
rrectness of i
l purpos

nf
ercia

orm
m

atio

If the LED does not flicker:

om

n in
or c

- Input 06 for "End output" and confirm with Q.

thi
te

sd

- -> Pull connector -1- off throttle valve positioner -2-.

iva

o
r
rp

cu
o

m
f

en
ng

t.
yi Co
Cop py
t. rig
gh ht
yri by

42 24 - Mixture preparation, Injection

cop Vo
by lksw
cted agen
Prote AG.
 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995
- Connect multimeter with aux. cables from V.A.G 1594 to measure voltage at contacts 3+4 of connector.
Specification: At least 11 V
- Switch off ignition

- -> Connect test box V.A.G 1598/18 to control unit wiring loom.
- Check wiring between test box and 6 pin connector for open circuit according to current flow diagram.
Contact 2+socket 16
Contact 4+socket 20
Wire resistance: Max. 1.5 ω
- Additionally check wires for short to one another.
Specification: ∞ω
. Volkswagen AG
gen AG d
If no wiring fault is detected
Vol
ksw and voltage was present
a oes
not between contacts 3+4:
y gu
db ara
ise nte
- Replace throttle
tho
r valve positioner (V60). eo
s au ra
c
s
If no wiring fault is detected and no voltage was present between contacts 3+4:
ce
le
un

pt
an
d
itte

- Check wiring from contact 3 to relay plate and from contact 4 to engine earth according to current flow
y li
erm

ab

diagram.
ility
ot p

wit
is n

h re
ole,

spec

1.15 - Checking throttle valve potentiometer

urposes, in part or in wh

t to the co

Special tools, testers, measuring instruments and auxiliary items required

rrectne

◆ Fault reader V.A.G 1551 or vehicle system tester V.A.G 1552 with cable V.A.G 1551/3
◆ Test box V.A.G 1598/18
ss

◆ Hand multimeter V.A.G 1526 or multimeter V.A.G 1715

o
cial p

◆ Adapter set V.A.G 1594

inform

◆ Current flow diagram

mer

atio
om

Test sequence
n
c

i
or

n thi
te

sd
a

- Connect fault reader V.A.G 1551 (V.A.G 1552) and select engine electronics control unit with the "Address
iv

o
pr

word" 01. When doing this the ignition must be switched on.
um
r
fo

(Connecting fault reader and selecting engine electronics control unit => Page 2 .)
en
ng

t.
yi Co
Cop py
-> Indicated on display:
t. rig
gh ht
pyri by
Vo
co
Rapid data transfer HELP
by lksw
Select function XX cted agen
Prote AG.

- Press keys 0 and 8 for the function "Read measured value block" and confirm entry with Q key.

-> Indicated on display:

Read measured value block HELP
Input display group number XXX

1.14 - Checking sender for throttle valve positioner 43

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995
- Press keys 0, 0 and 0 for "Display group number 0" and confirm entry with Q key.

-> Indicated on display:

(1...10 = Display zones)
AG. Volkswagen AG d
Read measured value block 0 agen oes
1 2 3 4 5 6 olksw not
y V gu
7 8 9 10 d b ara
rise nte
o
- Slowly open throttle valve fully and observe
auth the numerical figures in display zones 2 and
eo
r a3.
ss c

ce
e
Display zone 2:

nl

pt
du
The numerical figure must increase uniformly until throttle valve is 1/4 open and then remain

an
itte

y li
constant
erm

ab
Display zone 3:

ility
ot p

The numerical figure must increase uniformly over the entire

wit
, is n

range

h re
hole

spec
- Press ⇒key.
es, in part or in w

t to the co
- Press keys 0 and 6 for the function "End output" and confirm entry with the Q key.

If numerical figures in display zones 2 and 3 do not change as described:

rrectness of i
- Switch off ignition.
l purpos

nf
ercia

orm
m

atio
om

n in
or c

thi
te

sd
iva

o
r
rp

cu
o

m
f

en
ng

t.
yi Co
Cop py
t. rig
gh ht
pyri by
Vo
co lksw
by
cted agen
Prote AG.
- -> Pull connector -1- off throttle valve potentiometer -2-.
(5 pin connector for manual gearbox)
(7 pin connector for automatic gearbox)
- Connect multimeter with aux. cables from V.A.G 1594 to measure voltage at connector contacts
Manual gearbox to contacts 1+5
Automatic gearbox to contacts 1+7
- Switch on ignition and measure voltage
Specification: approx. 5 V
- Switch off ignition.

- -> Connect test box V.A.G 1598/18 to control unit wiring loom.
- Check wiring between test box 1598/18 and disconnected connector of throttle valve potentiometer for open
circuit according to current flow diagram.
5 pin connector (manual gearbox)
Contact 1+socket 17

44 24 - Mixture preparation, Injection

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995
Contact 2+socket 41
Contact 4+socket 18
Contact 5+socket 14
Wire resistance: Max. 1.5 ω

7 pin connector (automatic gearbox):

Contact 1+socket 17
Contact 2+socket 41
Contact 6+socket 18
Contact 7+socket 14
Wire resistance: max. 1.5ω

- Additionally check wires for short to one another.

Specification: ∞ω

If no wiring fault is detected and voltage was present between contacts 1+5 or 1+7:

- Replace lower part of injection unit.

If no wiring fault is detected and no voltage was present between contacts 1+5 or 1+7:

- Renew Mono Motronic control unit (J257)

=>Page 19 , item 2 .

1.16 - Checking coolant temperature sender

n AG. Volkswagen AG do
lkswage es n
o ot g
byV ua
Special tools, testers and auxiliary items ir se
d ran
tee
tho
u or
a ac
◆ Fault reader V.A.G 1551 or vehicle systemss tester V.A.G 1552 with cable V.A.G 1551/3
◆ Test box V.A.G 1598/18

ce
le
un

pt
◆ Hand multimeter V.A.G 1526 or multimeter V.A.G 1715

an
d
itte

y li
◆ Adapter set V.A.G 1594
rm

ab
◆ Current flow diagram
pe

ility
ot

wit
, is n

Test sequence

h re
hole

spec
- Connect fault reader V.A.G 1551 (V.A.G 1552) and select engine electronics control unit (address word 01);
es, in part or in w

t to the co
carry out selection at idling.
=> Page 2

rrectness of i
-> Indicated on display:
l purpos

Rapid data transfer HELP

Select function XX
nform
ercia

- Input 08 for "Read measured value block" function and confirm with Q.
m

a
com

-> Indicated on display:

tion in
r

Read measured value block HELP

te o

thi

Input display group number XX

s
iva

do
r
rp

cum
fo

- Input 01 for "Display group number" and confirm with Q.

en
ng

t.
- Note intake air temperature figure in display zone 2.
yi Co
op
- Determine possible cause of fault according to the table and continue with appropriate check.
C py
t. rig
gh ht
pyri by
Vo
co lksw
by
Display Cause Continuation of Prote
cted AG.
agen
check
app. 240 or Open circuit or => Page 46
app. -50 °C short to positive
App. 0 or app. Short to earth => Page 47
130°C

1.15 - Checking throttle valve potentiometer 45

 olkswagen AG
wag en AG. V
Caddy 1996 , Polo Classic 1996 olks➤
does
not
yV gu
Mono Motronic injection and
sed ignition system - Edition 11.1995
b ara
n ri tee
ho
ut or
Display Cause ss Continuation
a of ac
check

ce
e
nl

pt
du
Between 8...230 --- Only if spora-

an
itte

y li
or app. coolant dic faults

erm

ab
temperature1) have been

ility
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detected:2)

wit
, is n => Page 47

h re
hole

spec
1) If a temperature is displayed which deviates greatly from the ambient temperature of the sender, check
es, in part or in w

sender wiring for transfer resistances. For display group 0:

t to the co
125 corresponds to approx. 20 °C
25 corresponds to approx. 85 °C

rrectness of i
2) Check is only possible when the engine is cold.
l purpos

Continuation of check when display = approx. 240 or approx. -50°C:

nform
mercia

at
om

ion
c

in t
or

his
ate

do
priv

cum
for

en
ng

t.
yi Co
Cop py
ht. rig
rig ht
py by
co Vo
by lksw
cted agen
Prote AG.

- -> Pull 4 pin connector -1- of coolant temperature sender (G62).

- Bridge connector contacts 1+3 with aux. cables from V.A.G 1594 and observe display.

Display 0 or approx. 130 ° C:

- Replace coolant temperature sender -2-.

Display approx. 240 or approx. -50 ° C:

- Press ⇒ button.

- Input 06 for "End output" and confirm with Q.

- Switch off ignition
- -> Connect test box V.A.G 1598/18 to control unit wiring loom.
- Check wire between test box socket 42+4 pin connector contact 3 for open circuit according to current flow
diagram.
Wire resistance: Max. 1.5 ω
- Additionally check wire for short to battery positive.
Specification: ∞ω
- Check wire between test box socket 17+4 pin connector contact 1 for open circuit according to current flow
diagram.

46 24 - Mixture preparation, Injection

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995
Wire resistance: Max. 1.5 ω

If no fault in wire is detected:

- Renew Mono Motronic control unit (J257)

=>Page 19 , item 2 .

Continuation of check when display = 0 or approx.130 °C:

- -> Pull 4 pin connector -1- of coolant temperature sender (G62) -2-.

Display approx. 240 or approx. -50 ° C:

- Replace coolant temperature sender -2-.

Display 0 or approx. 130 ° C:

- Press ⇒ button.
- Input 06 for "End output" and confirm with Q.
- Switch off ignition
- Pull connector off Mono Motronic control unit.
- Check wire between control unit connector and 4 pin connector contact 3 for short to wire contact 1 and to
vehicle earth, according to current flow diagram.
n AG. Volkswagen AG do
Specification: ∞ω lkswage es n
Vo ot gu
by ara
ed nte
If no fault in wire is detected: oris eo
th
au ra
c
ss
- Renew Mono Motronic control unit (J257)
ce
e
nl

pt

=>Page 19 , item 2 .
du

an
itte

y li
erm

ab

Continuation of check when display = coolant temperature:

ility
ot p

wit
, is n

h re
hole

Functional check of sender

spec
es, in part or in w

t to the co

- ->
Read measured value block 1
1 2 3 4
rrectness of i

Observe coolant temperature figure in display zone 2. The temperature figure must
Increase uniformly and without interruption.
l purpos

Notes:
nf
ercia

orm

◆ If the display on fault reader jumps by 2...5 °C, it is a control unit fault and not caused by a defective sender.
m

atio
m

◆ If irregular engine running occurs in certain temperature ranges and the temperature figure does not increase
o

n in
c

without interruption, the temperature signal is temporarily interrupted and the sender must be renewed.
or

thi
te

sd
iva

- Press ⇒ key.
r
rp

cu
o

- In put 06 for "End output" and confirm with Q.

f

en
ng

t.
yi Co
Cop py
t. rig
gh ht
pyri by
Vo
co lksw
by
cted agen
Prote AG.

1.16 - Checking coolant temperature sender 47

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995

1.17 - Checking intake air temperature sender

Special tools, testers and auxiliary items

◆ Fault reader V.A.G 1551 or vehicle system tester V.A.G 1552 with cable V.A.G 1551/3
◆ Test box V.A.G 1598/18
◆ Hand multimeter V.A.G 1526 or multimeter V.A.G 1715
◆ Adapter set V.A.G 1594
◆ Current flow diagram
◆ Chilling spray (commercially available)

Test sequence
- Connect fault reader V.A.G 1551 (V.A.G 1552) and select engine electronics control unit (address word 01);
carry out selection with ignition switched on.
=> Page 2 wage
n AG. Volkswagen AG do
e
olks s no
yV t gu
-> Indicated on display: edb ara
is nte
or eo
Rapid data transfer HELP uth ra
a c
Select function XX ss

ce
e
nl

pt
- Input 08 for "Read measured value block" function and confirm with Q.
du

an
itte

y li
erm

ab
-> Indicated on display:

ility
ot p

wit
Read measured value block HELP
, is n

h re
Input display group number XX
hole

spec
- Input 02 for "Display group number" and confirm with Q.
es, in part or in w

t to the co
-> Indicated on display:
(1...4 = Display zones)

rrectness of i
Read measured value block 2
1 2 3 4
l purpos

- Note intake air temperature figure in display zone 4.

nf
ercia

Display Cause Continuation of orm

check
m

atio
om

Approx. -55 °C Open circuit or => Page 48

n in
or c

short to positive
thi
te

sd
a

Approx. 130 °C or Short to earth => Page 49

iv

o
r
rp

cu

higher
o

m
f

en
ng

t.
Approx. ambient --- => Page 50 op
yi Co
temperature1)
C py
ht. rig
rig ht
py by
1) If a temperature is displayed which deviates greatly from the ambient temperature of the sender, check co Vo
by lksw
sender wiring for transfer resistances.
cted agen
Prote AG.

Continuation of check when display = -55 °C:

- Remove air intake elbow.

48 24 - Mixture preparation, Injection

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995
- -> Pull 4 pin connector -1- off injection unit -2-.
- Bridge connector contacts 1+4 with aux. cables from V.A.G 1594 and observe display.

Display approx. 130 °C or higher:

- Replace injector bracket with intake air temperature sender (G42) =>Page 26 , item 3 .

Display approx. -55 °C:

- Press ⇒ button.
- Input 06 for "End output" and confirm with Q.

- Switch off ignition

- -> Connect test box V.A.G 1598/18 to control unit wiring loom.
- Check wire between test box socket 43+4 pin connector contact 4 for open circuit according to current flow
diagram.
Wire resistance: Max. 1.5 ω
- Additionally check wire for short to battery positive.
Specification: ∞ω
- Check wire between test box socket 17+4 pin connector contact 1 for open circuit according to current flow
diagram.
Wire resistance: Max. 1.5 ω
n AG. Volkswagen AG do
wage es n
If no fault in wire
yV
olkis
s detected: ot g
d b ua
e ran
ris tee
- Renewutho Mono Motronic control unit (J257) or
=>Page
ss
a 19 , item 2 . ac
ce
e
nl

pt
du

Continuation of check when display = 130 °C or higher:

an
itte

y li
erm

ab

- Remove air intake elbow.

ility
ot p

wit
, is n

h re
hole

spec
es, in part or in w

t to the co
rrectness of i
l purpos

nform
mercia

at
om

ion
c

in t
or

- -> Pull 4 pin connector -1- off injection unit -2-.

his
ate

do
priv

Display approx. -55 °C:

um
for

en
ng

t.
yi Co
Cop py
t. rig
gh ht
pyri by
Vo
o
by c lksw
cted agen
Prote
49
AG.
1.17 - Checking intake air temperature sender
 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995
- Replace injector bracket with intake air temperature sender (G42) =>Page 26 , item 3 .

Display approx. 130 °C or higher:

- Press ⇒ button.
- Input 06 for "End output" and confirm with Q.
- Switch off ignition
- Pull connector off Mono Motronic control unit.
- Check wiring to control unit connector at 4 pin connector contact 4 for short to wire contact 1 and to vehicle
earth.
Specification: ∞ω

If no wiring fault is detected:

- Renew Mono Motronic control unit (J257)
=>Page 19 , item 2 .

Continuation of check when display = ambient temperature:

- Remove air intake elbow.
AG. Volkswagen AG d
agen oes
olksw not
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au ra
ss c

ce
e
nl

pt
du

an
itte

y li
erm

ab
ility
ot p

wit
, is n

h re
hole

spec
es, in part or in w

t to the co
- -> Spray sender arrow with a commercial chilling spray and at the same time observe the temperature figure.

rrectness of i
The temperature figure must
decrease.
l purpos

- Note intake air temperature figure in display zone 4.

- Press ⇒ button.
- Input 06 for "End output" and confirm with Q.

nf
ercia

orm
m

atio
om

n in
c

1.18 - Checking injector

or

thi
te

sd
iva

o
r
rp

cu
Test conditions
o

m
f

en
ng

• Fuse 18 OK.
t.
yi Co
Cop py
t. rig
gh
Checking function
ht
pyri by
Vo
co
- Remove air intake elbow.
by lksw
cted agen
Prote AG.

50 24 - Mixture preparation, Injection

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995
- -> Start engine and run at idling speed, or if engine will not start, operate starter. The spray formation must
be visible on the
throttle valve.
- Switch off ignition and check injector (N30) for leaks.
Leakage must not exceed 2 drops per minute.

If no spray can be seen:

- Check fuel pressure regulator => Page 59 .

- Check activation.

Checking activation

Special tools, testers and auxiliary itemsgen AG. Volkswagen AG d

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olks not
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◆ Test box V.A.G 1598/18 ised b ara
nte
◆ Diode test lamp V.A.G t1527
ho
r eo
◆ Adapter set V.A.G 1594
ss
au ra
c
◆ Current flow diagram

ce
e
nl

pt
du

an
itte

Test sequence

y li
erm

ab
ility
ot p

- Remove air intake elbow.

wit
, is n

h re
hole

spec
es, in part or in w

t to the co
rrectness of i
l purpos

nform
mercia

at
om

ion
c

in t
or

his
te

- -> Pull 4 pin connector -1- off injection unit -2-.

a

do
riv

- Connect diode test lamp V.A.G 1527 with aux. cables from V.A.G 1594 to connector contacts 2 and 3.
p

cum
or

- Operate starter and check injector voltage supply.

f

en
ng

t.
LED must flicker
yi Co
Cop py
ht. rig
rig ht
LED flickers: py by
co Vo
by lksw
cted agen
Prote AG.
- Switch off ignition
- Renew injector.

1.18 - Checking injector 51

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995
If the LED does not flicker:

- Switch off ignition

- -> Connect test box V.A.G 1598/18 to control unit wiring loom.
- Check wire between 4 pin connector contact 3 and test box socket 7 for open circuit according to current
flow diagram (from the central connector to control unit = resistance wire).
Wire resistance: Max. 3.5 ω
- Check wire between 4 pin connector contact 2 and relay plate for open circuit according to current flow
diagram (from the central connector to relay plate = resistance wire).
Wire resistance: Max. 2.5 ω
- Additionally check wires for short to one another.
Specification: ∞ω

If no wiring fault is detected:

- Renew Mono Motronic control unit (J257)

=>Page 19 , item 2 .

Checking injector resistance

AG. Volkswagen AG d
agen oes
olksw not
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rise nte
tho eo
au ra
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ce
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un

pt
an
d
itte

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rm

ab
pe

ility
ot

wit
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- -> Pull 4 pin connector -1- off injection unit -2-. h re

hole

- Check injector resistance with multimeter and aux. cables from V.A.G 1594 on contacts 2+3 of connector spec
-2-:
es, in part or in w

Specification: 1.2...1.6 ω
t to the co

(at an ambient temperature of +15...30 °C)

rrectness of i

1.19 - Checking speed signal

l purpos

nform
ercia

Special tools, testers and auxiliary items

m

a
com

tio

◆ Fault reader V.A.G 1551 or vehicle system tester V.A.G 1552 with cable V.A.G 1551/3
n in
r
te o

◆ Hand multimeter V.A.G 1526 or multimeter V.A.G 1715

thi
s

◆ Test box V.A.G 1598/18

iva

do
r

◆ Adapter set V.A.G 1594

rp

cum
fo

◆ Current flow diagram

en
ng

t.
yi Co
Cop py
Test conditions
t. rig
gh ht
pyri by
Vo
co lksw
by
• Speedometer OK., checking: cted agen
Prote AG.

=> Repair group 90; Electrical system Electrical system

Test sequence

Note:

To check the speed signal the vehicle must be driven. To do this a second person is necessary.

52 24 - Mixture preparation, Injection

 n AG. Volkswagen AG do
Caddy 1996 , Polo Classic 1996 ➤
l wage
ksMono Motronic injection
es n and ignition system - Edition 11.1995
o ot gu
yV
edb ara
- Connect faultthoreader
ris V.A.G 1551 (V.A.G 1552) and selectnteengine eo electronics control unit (address word 01);
carry out selection
s au at idling. ra
c
=> Page s2

ce
e
nl

pt
du

an
-> Indicated on display:
itte

y li
erm

ab
Rapid data transfer HELP

ility
ot p

Select function XX

wit
, is n

h re
- Input 08 for "Read measured value block" function and confirm with Q.
hole

spec
es, in part or in w

-> Indicated on display:

t to the co
Read measured value block HELP
Input display group number XX

rrectness of i
- Input 04 for "Display group number" and confirm with Q.
l purpos

-> Indicated on display:

(1...4 = Display zones)

nf
ercia

orm
Read measured value block 4
m

atio
1 2 3 4
om

n in
or c

- Carry out test drive and when doing this observe display (2nd person necessary).

thi
te

sd
a

- Observe displayed figure in display zone 3:

iv

o
r

Specification:
rp

cu
o

m
f

0...4 km/h = 0

en
ng

t.
yi
4...7 km/h = >4
Co
op py
above 7 km/h = >7
t. C rig
gh ht
yri
- Press ⇒ key. p by
o Vo
by c
- Input 06 for "End output" and confirm with Q.
lksw
cted agen
Prote AG.

If no speed is indicated:
- Switch off ignition

- -> Connect test box V.A.G 1598/18 to control unit wiring loom.
- Connect multimeter to sockets 20+36 to measure voltage.
- Switch on ignition.
- Raise left front wheel or push vehicle. The voltage figure must fluctuate between
0...at least 4 V.

1.20 - Checking control unit voltage supply

Special tools, testers and auxiliary items

◆ Fault reader V.A.G 1551 or vehicle system tester V.A.G 1552 with cable V.A.G 1551/3
◆ Test box V.A.G 1598/18
◆ Hand multimeter V.A.G 1526 or multimeter V.A.G 1715
◆ Adapter set V.A.G 1594

1.19 - Checking speed signal 53

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995
◆ Current flow diagram

Check conditions

• Battery voltage at least 11 V

• Fuse 15 OK. agen
AG. Volkswagen AG d
oes
• Alternator OK Volksw not
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ise nte
Test sequence ut
hor eo
ra
s a c
s
- Connect fault reader V.A.G 1551 (V.A.G 1552) and select engine electronics control unit (address word 01);

ce
le
un

pt
carry out selection at idling.

an
d
itte

=> Page 2

y li
erm

ab
ility
ot p

-> Indicated on display:

wit
is n

h re
Rapid data transfer HELP
ole,

Select function XX

spec
urposes, in part or in wh

t to the co
- Input 08 for "Read measured value block" function and confirm with Q.

-> Indicated on display:

rrectne
Read measured value block HELP
Input display group number XX

ss o
- Input 02 for display group 02 and confirm with Q.
cial p

f inform
mer

-> Indicated on display:

atio
m

(1...4 = Display zones)

o

n
c

i
or

n
Read measured value block 2

thi
e

1 2 3 4
t

sd
iva

o
pr

cum
r
fo

- Read off figure displayed in display zone 3.

en
ng

t.
Specification: approx. battery voltage constant
yi Co
op
- Press ⇒ key.
C py
t. rig
gh
- Input 06 for "End output" and confirm with Q.
ht
pyri by
Vo
o
- Switch off ignition by c lksw
cted agen
Prote AG.

- -> Connect test box V.A.G 1598/18 to control unit wiring loom.

Checking voltage supply terminal 30

- Measure fault memory voltage supply with multimeter and aux. cables from V.A.G 1594 between test box
sockets 1+21:
Specification: Min. 11 V

If the measurement with V.A.G 1551/1552 does not indicate battery voltage:

Checking voltage supply terminal 15

- Switch on ignition.

54 24 - Mixture preparation, Injection

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995
- Measure control unit voltage supply with multimeter and aux. cables from V.A.G 1594 between test box
sockets 1+23:
Specification: Min. 11 V

If the specification is not obtained:

AG. Volkswagen AG d
agen oes
- Check wiring according toVocurrent
lksw flow diagram. not
gu
by ara
ed nte
oris eo
th
au ra
c
ss
1.21 - Checking air conditioner and air conditioner compressor signals

ce
le
un

pt
an
d
itte

y li
erm

ab
These signals from the air conditioner cause the initial control value for the idling stabilization to be increased

ility
ot p

when the air conditioner compressor switches in. Thereby the idling stabilization remains in the middle of the

wit
is n

regulating range.

h re
ole,

spec
Special tools, testers and auxiliary items
urposes, in part or in wh

t to the co
◆ Fault reader V.A.G 1551 or vehicle system tester V.A.G 1552 with cable V.A.G 1551/3
◆ Test box V.A.G 1598/18
◆ Hand multimeter V.A.G 1526 or multimeter V.A.G 1715

rrectne
◆ Adapter set V.A.G 1594
◆ Current flow diagram

ss o
cial p

f
Test conditions

inform
mer

• Function of air conditioner OK.

atio
m

• Air conditioner switched off

o

n
c

i
or

n
• No faults stored in fault memory
thi
te

=> Page 3 , interrogating fault memory sd

iva

o
r

• Interior of vehicle has room temperature (above 15 ° C)

p

cum
r
fo

en
ng

t.
yi
Test sequence
Co
Cop py
t. rig
gh ht
yri
- Connect fault reader V.A.G 1551 (V.A.G 1552) and select engine electronics control unit (address word 01);
p by
co Vo
by lksw
carry out selection at idling. Prote
cted AG.
agen
=> Page 2

-> Indicated on display:

Rapid data transfer HELP
Select function XX

- Input 08 for "Read measured value block" function and confirm with Q.

-> Indicated on display:

Read measured value block HELP
Input display group number XX

- Input 01 for "Display group number" and confirm with Q.

-> Indicated on display:

(1...4 = Display zones)
Read measured value block 1
1 2 3 4

- Observe display zone 4 -8 digit number block-:

4th and 5th position from right must display 0

Display: 01000000

- Switch on air conditioner (lowest temperature and highest blower speed).

1.20 - Checking control unit voltage supply 55

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995
4th and 5th position from right must now display 1
Display: 01011111
4th position from right = air conditioner switched on
5th position from right = air conditioner compressor switched on

If the display does not indicate as described:

- -> Connect test box V.A.G 1598/18 to control unit wiring loom.
- Check wiring between test box sockets 33 and 35 and the air conditioner for open circuit according to current
flow diagram.
Wire resistance: Max. 1.5 ω

. Volkswagen AG
gen AG
1.22 - Matching automatic gearbox control nunit
ot g and throttle valve potentiometer to one
wa oes d
olks
yV
another ris
ed b ua
ran
t ee
ho
aut or
ac
ss
Note:
ce
le
un

pt
an
d
itte

y li

The automatic gearbox control unit (J217) and throttle valve potentiometer (G69) must be matched to one
rm

ab

another after the following work has been completed:

pe

ility
ot

wit
, is n

h re

◆ Renewal of automatic gearbox control unit

hole

◆ Renewal of injection unit (lower part)

spec
es, in part or in w

t to the co

Matching

- Using fault reader V.A.G. 1551 (or vehicle system tester V.A.G 1552) bring system to basic setting:
rrectness of i

=> Automatic gearbox 096; Repair Group 01; Self-diagnosis; Introduction of basic setting Self-diagnosis Intro‐
l purpos

duction of basic setting

nform
mercia

1.23 - Checking signal for automatic gearbox control unit

com

tion in
r
te o

thi
s
iva

do

Special tools, testers, measuring instruments and auxiliary items required

r
rp

cum
fo

en
ng

t.
◆ Fault reader V.A.G 1551 or vehicle system tester V.A.G 1552 with cable V.A.G 1551/3
yi Co
op
◆ Test box V.A.G 1598/18
C py
t. rig
gh
◆ Hand multimeter V.A.G 1526 or multimeter V.A.G 1715
ht
pyri by
Vo
o
◆ Adapter set V.A.G 1594
c by lksw
cted agen
◆ Current flow diagram Prote AG.

Test conditions

• No faults stored in fault memory

=> Page 3 , interrogating fault memory

56 24 - Mixture preparation, Injection

 Caddy 1996 , Polo Classic 1996 ➤
. Volkswagen AG
Mono Motronic injection and w gen AG
aignition system - dEdition
oes 11.1995
lks n o ot g
yV ua
db
Test sequence ris
e ran
tee
tho or
au ac
- Connect fault reader V.A.G 1551 (V.A.G 1552)
ss and select engine electronics control unit with the "Address

ce
e
word" 01. When doing this the ignition must be switched on.

nl

pt
du
(Connecting fault reader and selecting engine electronics control unit => Page 2 .)

an
itte

y li
erm

ab
-> Indicated on display:

ility
ot p

wit
, is n
Rapid data transfer HELP

h re
Select function XX

hole

spec
es, in part or in w
- Press keys 0 and 8 for the function "Read measured value block" and confirm entry with Q key.

t to the co
-> Indicated on display:

rrectness of i
Read measured value block HELP
Input display group number XXX
l purpos

- Press keys 0, 0 and 1 for "Display group number 1" and confirm entry with Q key.

nf
ercia

o
-> Indicated on display:

rm
m

atio
(1...4 = Display zones)
om

n in
c

Read measured value block 1

or

thi
e

1 2 3 4
t

sd
iva

o
r
rp

cu
- Observe display zone 4 -8 digit number block-:
o

m
f

en
ng

- Selector lever at P or N
t.
yi Co
Cop py
t. rig
gh
1st position from right must display 0
ht
pyri by
Display: 01000010
o Vo
by c lksw
cted agen
Prote AG.

- Selector lever at 1, 2, 3, D or R

1st position from right must display 1

Display: 01000011

- Press ⇒key.
- Press keys 0 and 6 for the function "End output" and confirm entry with the Q key.

If the display does not indicate as described:

- Switch off ignition.

- -> Connect test box V.A.G 1598/18 to control unit wiring loom.
- Check voltage with multimeter and aux. cables from V.A.G 1594 between test box sockets 12+23:
Selector lever at P or N
Specification: Min. 11 V
Selector lever in 1, 2, 3, D or R
Specification: 0 V

If the specifications are not attained:

1.23 - Checking signal for automatic gearbox control unit 57

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995
- Check wiring according to current flow diagram.

1.24 - Matching engine electronic control unit to electronic immobilizer

Special tools, testers and auxiliary items

◆ Fault reader V.A.G 1551 or vehicle system tester V.A.G 1552 with cable V.A.G 1551/3

Test conditions

• Authorized vehicle key required

Work sequence

- -> Fold down left shelf.

- Connect fault reader (or vehicle system tester) with cable V.A.G 1551/3.
- Switch on ignition.
- Operate fault reader taking into account the information on the display:
- Input 1 for "Rapid data transfer".
- Input 25 for address word "Immobilizer" and confirm with Q.
- After the immobilizer control unit has registered, press ⇒ key.
AG. Volkswagen AG d
agen
-> Indicated on display: olksw
oes
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ara
Rapid data transfer HELP ed
Select function XX ris nte
ho eo
aut ra
ss c
- Input 10 for "Adaption" function and confirm with Q.
ce
le
un

pt
an
d
itte

y li
-> Indicated on display:
rm

ab
pe

ility
Adaption
ot

wit

Feed in channel number XX

, is n

h re
hole

spec

- Input 00 for channel number 0 and confirm with Q.

es, in part or in w

t to the co

-> Indicated on display:

Adaption Q
Erase learnt values?
rrectness of i
l purpos

- Confirm entry by pressing Qkey.

-> Indicated on display:

nform
ercia

Adaption
m

Learnt values have been erased

com

tion in
r
te o

- Conclude adaption by pressing ⇒ key.

thi
s
iva

- Input 06 for "End output" and confirm with Q.

do
r
rp

cum
fo

en
ng

t.
yi Co
Cop py
ht. rig
rig ht
py by

58 24 - Mixture preparation, Injection

co Vo
by lksw
cted agen
Prote AG.
 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995
- Switch off ignition

Note:
The identity of the engine control unit is read into the immobilizer control unit when next switching the ignition
on.

1.25 - Checking fuel pressure regulator and holding pressure

Special tools, testers and auxiliary items

◆ Pressure tester V.A.G 1318
◆ Adapter 1318/1
◆ Adapter 1318/10
◆ Adapter 1318/11

Test conditions
• Fuel pump delivery rate OK, checking:

=> Repair group 20; Removing and installing parts of the fuel supply system; Checking fuel pump Removing
and installing parts of the fuel supply system Checking fuel pump
Test sequence
Note:
Check whether a coded radio is installed as during the forthcoming work sequences the battery earth strap
must be disconnected. Obtain radio code first if necessary.
Warning!
Fuel system is under pressure! Before opening the system place a cloth around the connection. Then release
pressure by carefully loosening the connection.

AG. Volkswagen AG d
agen oes
olksw not
byV gu
ara
ed
ris nte
ho eo
aut ra
ss c
ce
le
un

pt
an
d

- -> Connect pressure gauge V.A.G 1318 with adapter 1318/1 , /11 and /23 between fuel supply pipe -1- and
itte

y li

injection unit:
erm

ab
ility

- Open pressure gauge tap (lever in direction of flow).

ot p

- Start engine and run at idling speed.

wit
is n

h re
ole,

spec

If the engine does not start:

urposes, in part or in wh

t to the co
rrectness o
cial p

f inform
mer

atio
om

n
c

i
or

n thi
te

sd
iva

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pr

cum
r
fo

en
ng

t.
yi Co
Cop py
ht. rig
rig ht
py by
co Vo

59
by lksw
cted agen
Prote 1.24 - Matching engine electronic control unit to electronic immobilizer
AG.
 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995
- -> Pull fuel pump relay (J17) out of relay plate (relay position 12).

Note:
If the relay cannot be removed from the relay plate without tools then first disconnect battery earth strap.
- Connect remote control V.A.G 1348/3A with adapter cable V.A.G 1348/3-2 to contact 4 and battery positive
(+).
- Operate remote control.

- Check fuel pressure.

Specification: Approx. 0.8...1.2 bar

If the specification is exceeded or not reached:

AG. Volkswagen AG d
agen oes
olksw not
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nl

- -> Dismantle the pressure regulator as follows:

pt
du

an
itte

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erm

ab

Note:
ility
ot p

wit

First remove the intake air temperature sender -8- and unclip the cable guide -6-.
, is n

h re
hole

spec

- Clean the individual parts of the pressure regulator and the injection unit upper part.
es, in part or in w

t to the co

Assembling
- Place the membrane -1- as shown in the injection unit upper part.
rrectness of i

- Insert the spring -2- and compress it with the pressure regulator upper part -3-.
- Carefully tighten the retaining ring -4- with screws -5- (tightening torque: 1.5 Nm).
l purpos

- Install the intake air temperature sender -8- and tighten screw -7- to
nf
ercia

5 Nm.
or

- Clip on the cable guide -6-.

m
m

atio
om

n in

- Repeat the pressure regulator test.

or c

thi
te

sd
iva

If the specification is again not reached:

o
r
rp

cu
o

m
f

en
ng

- Renew injection unit upper part.

t.
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Cop py
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If the specification is exceeded:
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- Check return pipe for blockage, if necessary renew injection unit upper part.
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Prote AG.
- Switch off ignition or remote control and check holding pressure.
Specification:

60 24 - Mixture preparation, Injection

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995
at least 0.5 bar after 5 minutes.

If the holding pressure drops below specification:

- Check pipe connections, O rings on injector and injectors for leaks.

- Check fuel pump non-return valve.

=> Repair group 20; Removing and installing parts of the fuel supply system; Checking fuel pump Removing
and installing parts of the fuel supply system Checking fuel pump

If the pressure drops again:

- Renew injection unit upper part.

Note:

The injection unit upper part and components of the fuel pressure regulator are matched to one another. The
pressure regulator cannot be repaired. If the pressure regulator is defective the complete injection unit upper
part must be renewed.

1.26 - Checking intake air system for leaks (unmetered

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Special tools, testers and auxiliary items auth eo
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◆ Fault reader V.A.G 1551 or vehicle system tester V.A.G 1552 with cable V.A.G 1551/3
nl

pt
du

◆ Engine leak detector spray G 001 800 A1

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Test sequence

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Notes:
hole

spec
es, in part or in w

◆ The vacuum in the intake system will cause the leak detector spray to be drawn in with the unmetered air.

t to the co
The leak detector spray reduces the ignitability of the mixture. This leads to a drop in engine speed and to
a change of Lambda probe reading.
◆ The safety precautions listed on the container must be adhered to.

rrectness of i
- Connect fault reader V.A.G 1551 (V.A.G 1552) and select engine electronics control unit (address word 01);
l purpos

carry out selection at idling.

=> Page 2
nf
ercia

orm

-> Indicated on display:

m

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om

Rapid data transfer HELP

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Select function XX
thi
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- Input 08 for "Read measured value block" function and confirm with Q.
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-> Indicated on display:
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Read measured value block HELP gh ht
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Input display group number XX cop Vo
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- Input 00 for "Display group number" and confirm with Q.

-> Indicated on display:

(1...10 = Display zones)
Read measured value block 0
1 2 3 4 5 6
7 8 9 10

- Observe reading in display zone 5 (Lambda reading) and note range of reading.

1.25 - Checking fuel pressure regulator and holding pressure 61

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995
- Systematically spray parts of the intake system with engine leak detector spray.
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If the engine speed drops and the yreading Volks
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- Check for leaks in the area
uth of intake system sprayed and eliminate leak.
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itte

1.27 - Checking intake air preheating

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ility
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Special tools, testers and auxiliary items

h re
hole

spec
◆ Hand vacuum pump V.A.G 1390
es, in part or in w

t to the co
Test conditions

rrectness of i
• Regulating flap vacuum unit not leaking
l purpos

Checking regulating flap

nform
ercia

- Loosen air cleaner upper part and remove filter element.

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- -> Check position of regulating flap.

Regulating flap must close-off the warm air intake -2-
- Pull vacuum pipe from vacuum unit -1- off temperature regulator -3- (in air intake elbow).
- Connect vacuum pipe to hand vacuum pump V.A.G 1390.
- Operate pump and check ease of movement of the regulating flap and function of the vacuum unit.
Regulating flap must close off the cold air
intake -4-

Checking temperature regulator

- Connect vacuum pipe to temperature regulator.

- Start engine and run at idling speed.

62 24 - Mixture preparation, Injection

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995
- -> Check position of regulating flap after max. 20 seconds.

Temperature of tempera‐ Regulating flap position

ture regulator
Below 35 °C Cold air inlet -4- closed
Above 45 °C Warm air intake -2- closed
Between 35 and 45 °C Between cold and warm
air intake

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c

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for

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1.27 - Checking intake air preheating 63

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995

28 - Ignition system

1 - Mono-Motronic injection and ignition system

1.1 - Mono-Motronic injection and ignition system
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1.2 - Servicing ignition part
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Notes:
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◆ Only the components which specifically relate to the ignition system are dealt with here. For the other com‐

wit
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h re
ponents of the injection and ignition system => Repair group 24.
hole

◆ The injection and ignition system control unit is equipped with self diagnosis.

spec
◆ Components marked with * are checked via the self diagnosis.
es, in part or in w

t to the co
=> Page 3 , interrogating fault memory
◆ For trouble-free operation of the electrical components a voltage of at least 11.5 V is necessary.
◆ During some checks it is possible that the control unit will recognise and store a fault. Therefore after com‐

rrectness of i
pleting all checks and repairs the fault memory must be interrogated and if necessary erased.
=> Page 3 , interrogating fault memory
l purpos

Safety precautions => Page 67

nf
ercia

or
Test data, spark plugs => Page 68
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64 28 - Ignition system
 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995

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is n

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urposes, in part or in wh

t to the co
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cial p

f inform
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1 HT cable
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◆ Check for continuity
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rig
2 Suppressor
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◆ 0.6...1.4 kω
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3 10 Nm
4 Ignition transformer (N152) with output stage (N157)
◆ Checking ignition transformer
=> Page 73
◆ Checking ignition transformer output stage => Page 73
5 Connector
6 Earth strap
7 Spark plug connector
◆ 4...6 kω

1.2 - Servicing ignition part 65

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995

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8 Spark plug, 25 Nm
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◆ Type and electrode gap

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=> Page 68
h re
hole

spec

9 25 Nm
es, in part or in w

10 Clamp
t to the co

11 O ring
◆ Renew if damaged
rrectness of i

12 Ignition distributor with Hall sender (G40)*

l purpos

◆ Installing => Page 68

◆ Checking and adjusting ignition timing => Page 69
◆ Checking Hall sender
nf
ercia

=> Page 71
orm
m

13 Dust cap
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66 28 - Ignition system
 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995

AG. Volkswagen AG d
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14 Rotor arm
◆ Marking: R1
nf
ercia

◆ 0.6...1.4 kω
rm
m

atio

15 Distributor cap
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◆ Check for cracks and signs of tracking

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◆ Check contact wear

thi
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◆ Clean before fitting

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◆ Check carbon brush for wear and freedom of movement

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16 Screening cap
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1.3 - Safety precautions
agen
Prote AG.

To prevent injuries to persons and/or damage to the injection and ignition system, the following must be ob‐
served:
◆ Do not touch or pull off ignition wiring when engine is running or turning at starter speed.
◆ The ignition must be switched off when disconnecting or connecting injection and ignition system wiring as
well as test instrument cables.
◆ If the engine is to be turned at starter speed, without starting, e.g. when checking compressions, pull plug
off Hall sender (distributor).
◆ Do not connect a capacitor to terminal 1 (-).
◆ Do not replace 1 kω (identification: R1) with a different type even for radio interference suppression.

1.2 - Servicing ignition part 67

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995
◆ For suppression purposes only 1 kω resistances are to be used on the H.T. leads and 5 kω spark plug
connectors.

1.4 - Adjustment data, Spark plugs

Engine codes 1F ADZ

Ignition timing1)
Test figure 4...8 ° before TDC 4...8 ° before TDC
Adjustment figure 6 ± 1 ° before TDC 6 ± 1 ° before TDC
Marking => Page 70 , => Page 70 ,
Fig. V28-0895 Fig. V28-0895
Engine speed 700...1000 rpm 775...975 rpm
Firing order 1-3-4-2 1-3-4-2
Spark plugs1)
VW/Audi 101 000 036 AB 101 000 036 AA
101 000 040 AD
Manufacturer's desig. BUR 5 ET BUR 6 ET
14 GH-7 DTUR
Electrode gap 0.7...0.9 mm 0.7...0.9 mm
VW/Audi 101 000 050 AA 101 000 050 AC
Manufacturer's desig. W 8 LTCR W 7 LTCR
Electrode gap 0.9...1.1 mm 0.9...1.1 mm
Tightening torque 25 Nm 25 Nm
AG. Volkswagen AG d
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1) The up-to-date figures
ed by and the spark plug change intervals: gu
ara
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=> aut
Exhaust emissions test binder ra
ss c
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nl

pt
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an
itte

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1.5 - Installing distributor

erm

ab
ility
ot p

wit
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hole

spec
es, in part or in w

t to the co
rrectness of i
l purpos

nf
ercia

orm
m

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c

- -> Set flywheel -A- or drive plate -B- to TDC No. 1 cylinder.
or

thi
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Prote AG.

68 28 - Ignition system
 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995

Engine removed
- -> Set vibration damper (V-belt pulley) to TDC No. 1 cylinder.

- -> Align oil pump shaft drive tongue with threaded hole.

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ility
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spec
es, in part or in w

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- -> Insert distributor so that the rotor arm points to No. 1 cylinder mark on the distributor body.
- Before fitting, clean distributor cap and check for cracks and signs of tracking, renew if necessary.
- Checking and adjusting ignition timing =>Page 69 .
rrectness of i
l purpos

1.6 - Checking and adjusting ignition timing

nf
ercia

orm
m

atio

Special tools, testers and auxiliary items

om

n in
c

◆ Fault reader V.A.G 1551 or vehicle system tester V.A.G 1552 with cable V.A.G 1551/3
or

thi
e

◆ Ignition tester V.A.G 1767 or V.A.G 1367 with HT pick-up clamp V.A.G 1367/8
t

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iva

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Check conditions
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• Engine oil temperature min. 80 °C t. Cop py
• No faults stored in fault memory
rig
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1.5 - Installing distributor 69

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Caddy 1996 , Polo Classic 1996tho ➤ tee
or
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Mono Motronic injection and
ss
a
ignition system - Edition 11.1995 ac

ce
e
nl

pt
=> Page 3 , interrogating fault memory

du

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itte

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erm

ab
ility
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wit
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hole

spec
es, in part or in w

t to the co
rrectness of i
l purpos

nf
ercia

orm
m

atio
m

Test sequence
o

n in
or c

thi
te

- -> Connect ignition tester V.A.G 1767 or ignition tester V.A.G 1367 with HT pick-up clamp V.A.G 1367/8.

sd
iva

o
- Connect fault reader V.A.G 1551 (V.A.G 1552) and select engine electronics control unit (address word 01);
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carry out selection at idling.
f

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t.
=> Page 2
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-> Indicated on display: p by
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Rapid data transfer HELP cted agen
Prote AG.
Select function XX

- Input 04 for "Initiate basic setting" and confirm with Q.

-> Indicated on display:

Basic setting HELP
Input display group number XX

- Input 00 for "Display group number" and confirm with Q.

-> Indicated on display:

(1...10 = Display zones)
System in basic setting 0
1 2 3 4 5 6
7 8 9 10

- Check ignition timing.

Specification: 4..8 ° before TDC1)

With stroboscope:

- -> Direct at ignition timing notch.

- If necessary adjust ignition timing by turning the distributor:

70 28 - Ignition system
 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995
Setting figure: 6 ± 1° before TDC1)

1) Up-to-date specifications:

=> Exhaust emissions test binder

- Press ⇒ key.
- Input 06 for "End output" and confirm with Q.

1.7 - Checking ignition timing control

Special tools, testers and auxiliary items

◆ Ignition tester V.A.G 1767 or V.A.G 1367 with HT pick-up clamp V.A.G 1367/8

Check conditions

• No faults stored in fault memory

=> Page 3 , interrogating fault memory
• Engine oil temperature min. 80 °C
• Ignition timing OK., checking
=> Page 69

Test sequence

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- -> Connect ignition tester V.A.G 1767 or ignition tester V.A.G 1367 with HT pick-up clamp V.A.G 1367/8.
an
itte

y li

- Start engine and run at idling speed.

erm

ab

- Set ignition tester to 3000 rpm.

ility
ot p

- Slowly increase speed to slightly above 3000 rpm until the ignition timing (advance figure) is indicated.
wit
, is n

Specification:
h re
hole

30...42 ° BTDC
spec
es, in part or in w

t to the co

1.8 - Checking Hall sender

rrectness of i
l purpos

Special tools, testers and auxiliary items

nform
ercia

◆ Test box V.A.G 1598/18

◆ Hand multimeter V.A.G 1526 or multimeter V.A.G 1715
m

at

◆ Adapter set V.A.G 1594

om

ion

◆ Current flow diagram

c

in t
or

his
ate

Test conditions
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• Fault on Hall sender recognised by self diagnosis

n

t.
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rig ht
py by
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Prote AG.

1.6 - Checking and adjusting ignition timing 71

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995
Note:

When the fault memory is interrogated with engine stationary without having agenoperated the starter
AG. Volkswagen AG d for at least 6
oes
seconds, the fault "Hall sender -G40, no signal" will be displayed, even
olksifwno fault is present. not
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es, in part or in w

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rrectness of i
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Test sequence

nform
- Pull plug off Hall sender (distributor).
ercia

- -> Connect multimeter to measure voltage with aux. cables from V.A.G 1594 to the outer contacts of the
m

at
plug.
om

io
- Switch on ignition.

n
c

in t
or

Specification: At least 9 V

his
te

- Switch off ignition

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- -> Connect test box V.A.G 1598/18 to control unit wiring loom.
- Check wiring between test box and 3 pin connector for open circuit according to current flow diagram.
Contact 1+socket 20
Contact 2+socket 13
Contact 3+socket 8
Wire resistance: Max. 1.5 ω
- Additionally check wires for short to one another.
Specification: ∞ω

If no wiring fault is detected and voltage was present between contacts 1+3:

- Renew distributor with Hall sender

=>Page 66 , Item 12 .

If no wiring fault is detected and no voltage was present between contacts 1+3:

- Renew Mono Motronic control unit (J257)

=>Page 19 , item 2 .

72 28 - Ignition system
 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995

1.9 - Checking ignition transformer

Special tools, testers and auxiliary items

◆ Hand multimeter V.A.G 1526 or multimeter V.A.G 1715

◆ Adapter set V.A.G 1594

Test sequence

- Pull connector and H.T. cable off ignition transformer (N152).

- -> Check primary resistance with hand multimeter V.A.G 1526 between terminals 1 and 15.
Specification: 0.5...0.7 ω
- Check secondary resistance with hand multimeter between terminals 4 and 15.
Specification: 3...4 kω

If the specifications are not attained:

- Replace ignition transformer.

AG. Volkswagen AG d
agen oes
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1.10 - Checking ignition transformer output stage
r nte
tho eo
au ra
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un

pt

Special tools, testers and auxiliary items

an
d
itte

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rm

ab

◆ Test box V.A.G 1598/18

pe

ility
ot

◆ Hand multimeter V.A.G 1526 or multimeter V.A.G 1715

wit
, is n

◆ Diode test lamp V.A.G 1527

h re
hole

◆ Adapter set V.A.G 1594

spec

◆ Current flow diagram

es, in part or in w

t to the co

Check conditions
rrectness of i
l purpos

nform
mercia

a
com

tion in
r
te o

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t.
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• Hall sender OK.
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gh by
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c by lksw
cted agen
Prote AG.

1.9 - Checking ignition transformer 73

 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995
• Ignition transformer OK.

Checking voltage supply

- Pull 3 pin plug off ignition transformer.

- -> Connect multimeter to measure voltage with aux. cables from V.A.G 1594 to the contacts 1+3 of the
disconnected connector.
- Switch on ignition.
Specification: Min. 11 V

If no voltage is present:

- Switch off ignition.

- Check wire between 3 pin connector contact 1 and earth for open circuit according to current flow diagram.
Wire resistance: Max. 1.5 ω
- Check wire between 3 pin connector contact 3 and relay plate for open circuit according to current flow
diagram.
Wire resistance: Max. 1.5 ω G. Volkswage nA n AG d
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Checking activation by
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- Disconnect plug for injector and intake
au air preheating from the injection unit. ra
c
ss

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nl

pt
du

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itte

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erm

ab
ility
ot p

wit
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hole

spec
es, in part or in w

t to the co
rrectness of i
l purpos

- -> Connect diode test lamp V.A.G 1527 with aux. cables from V.A.G 1594 and adapters V.A.G 1594/15 to nf
ercia

contacts 2+3 of connector -4-.

or

- Operate starter and check ignition signal from Mono-Motronic control unit.
m
m

atio

LED must flicker

om

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or c

thi

The LED does not flicker:

te

sd
iva

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f

en
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t.
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cted agen
Prote AG.

- -> Connect test box V.A.G 1598/18 to control unit wiring loom.
- Check wire between test box socket 24+3 pin connector contact 2 for open circuit according to current flow
diagram.
Wire resistance: Max. 1.5 ω
- Additionally check wires for short to one another.
Specification: ∞ω

74 28 - Ignition system
 Caddy 1996 , Polo Classic 1996 ➤
Mono Motronic injection and ignition system - Edition 11.1995
If no wiring fault is detected and voltage was present between contacts 1+3:
n AG. Volkswagen AG do
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- Renew Mono Motronic control unit (J257) yV
olks ot g
ua
=>Page 19 , item 2 . ir se
d b ran
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tho
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If the voltage supply and activation
ss is OK.:
a ac

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le
un

pt
an
d
itte

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erm

ab
ility
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wit
is n

h re
ole,

spec
urposes, in part or in wh

t to the co
rrectness o
cial p

f i
- Connect 3 pin plug and H.T. cable to ignition transformer.

nform
- -> Connect diode test lamp with aux. cables and clamps to the contacts 1 and 15 on ignition transformer.
mer

atio
om

n
c

Warning!

i
or

n thi
e

During the following test do not touch the terminals of the ignition transformer or test cables.
t

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iva

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pr

cum
r
fo

en
ng

- Operate starter.
t.
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The LED must flicker, Cop py
. rig
if necessary renew output stage.
t
gh ht
pyri by
Vo
co lksw
by
cted agen
Prote AG.

1.10 - Checking ignition transformer output stage 75