SECTION 5 TROUBLESHOOTING

Group 1 Before Troubleshooting ----------------------------------------------------------------------------------- 5-1

Group 2 Hydraulic and Mechanical System ---------------------------------------------------------------- 5-4
Group 3 Electrical System -------------------------------------------------------------------------------------------- 5-24
GROUP 1 BEFORE TROUBLESHOOTING

1. INTRODUCTION
When a trouble is occurred in the machine, this section will help a service man to repair the machine
with easy.
The trouble of machine is parted Hydraulic & Mechanical system and Electrical system.
At each system part, a service man can check the machine according to the troubleshooting process
diagram.

Hydraulic &
GROUP 2
Mechanical part

Troubles occur

Electrical part GROUP 3

5-1
2. DIAGNOSING PROCEDURE
To carry out troubleshooting efficiently, the following steps must be observed.

STEP 1. Study the machine system

Study and know how the machine is operating,
how the system is composing, what kinds of
function are installed in the machine and what
are specifications of the system components by
the machine service manual.
Especially, deepen the knowledge for the
related parts of the trouble.
13031SH02

STEP 2. Ask the operator

Before inspecting, get the full stor y of
malfunctions from a witness --- the operator.
1) How the machine is used and when it is
serviced?
2) When the trouble was noticed and what
work the machine was doing at that time?
3) What is the phenomenon of the trouble?
Was the trouble getting worse, or did it
come out suddenly for the first time?
4) Did the machine have any troubles
previously? If so, which parts were repaired
13031SH03
before.

STEP 3. Inspect the machine

Before starting troubleshooting, check the
machine for the daily maintenance points as
shown in the operator's manual.
And also check the electrical system including
batteries, as the troubles in the electrical system ON THE
INSPECTION
such as low battery voltage, loose connections
and blown out fuses will result in malfunction of
6-2(3) 140-7
the controllers causing total operational failures
of the machine.

5-2
STEP 4. Inspect the trouble actually on the
machine
In case that some trouble cannot be confirmed,
obtain the details of the malfunction from the
operator.
Also, check if there are any in complete
connections of the wire harnesses are or not.

6-3(1) 140-7

STEP 5. Perform troubleshooting

According to where the trouble parts are
located, hydraulic & mechanical system part or
electrical system part or mechatronics system
part, perform troubleshooting the machine refer
to the each system part's troubleshooting
process diagram.

13031SH05

STEP 6. Trace a cause

Before reaching a conclusion, check the most
suspectible causes again. Try to trace what the
real cause of the trouble is.

Make a plan of the appropriate repairing

procedure to avoid consequential malfunctions.

6-3(3) 140-7

5-3
GROUP 2 HYDRAULIC AND MECHANICAL SYSTEM

1. INTRODUCTION
1) MACHINE IN GENERAL
(1) If even a minor fault is left intact and operation is continued, a fatal failure may be caused,
entailing a large sum of expenses and long hours of restoration.
Therefore when even a small trouble occurs, do not rely on your intuition and experience, but look
for the cause based on the troubleshooting principle and perform maintenance and adjustment to
prevent major failure from occurring. Keep in mind that a fault results from a combination of
different causes.
(2) The following lists up commonly occurring faults and possible causes with this machine. For the
troubleshooting of the engine, refer to the coming troubleshooting and repair.
(3) When carrying out troubleshooting, do not hurry to disassemble the components.
It will become impossible to find the cause of the problem.
(4) Ask user or operator the following.
① Was there any strange thing about machine before failure occurred?
② Under what conditions did the failure occur?
③ Have any repairs been carried out before the failure?

(5) Check before troubleshooting.

① Check oil and fuel level.
② Check for any external leakage of oil from components.
③ Check for loose or damage of wiring and connections.

5-4
2. DRIVE SYSTEM
1) UNUSUAL NOISE COMES OUT OF PUMP CONNECTION

Cause Remedy
YES
Coupling element Disassemble
is broken. and repair.
Remove dust
plug under engine
flywheel and
YES
check if rubber Replace hub or
pieces or particles retighten
are not present. Coupling hub setscrew.
spline is worn or
NO hub fastening
setscrew is slack.
If hydraulic pump or engine is
suspected as a culprit refer to this
NO
manual "Structure and function".

5-5
 2) ENGINE STARTS BUT MACHINE DOES NOT OPERATE AT ALL

Cause Remedy
NO
Replenish
specified oil to
the standard
Is oil level in Abnormal noise level.
hydraulic oil YES YES
comes out of Hydraulic pump is Disassemble
tank within hydraulic pump
standard level? broken. and repair.

Do not hydraulic Abnormal noise

pump and pump YES comes out of YES
connections See item 1).
YES pump
make abnormal connection at page 5-5
noise?

Is primary pilot
pressure within ⓐ
NO standard level?

YES
Clean pilot
Is not pilot piping piping interior or
YES clogged or is not
repair piping.
oil leakage present
on pilot piping?
Pilot valve is Disassemble
NO
ⓐ faulty. and repair.
YES
Pilot relief valve is Repair or
Is gear pump faulty. replace.
NO delivering oil?
Gear pump is Disassemble
NO
broken. and repair.

5-6
3. HYDRAULIC SYSTEM
1) HYDRAULIC OIL IS CLOUDY

Cause Remedy
YES
Water is mixed. Put hydraulic oil
still, separate
Drop hydraulic oil water and
sample on hot dispose it or
plate and check if replace hydraulic
foams come up. oil.

Air is intruded. Check suction

NO
line and return
line and eliminate
the air intruding
source.

2) HYDRAULIC OIL TEMPERATURE HAS RISEN ABNORMALLY

Cause Remedy
NO
Replenish
specified oil to
the standard
Is hydraulic oil level.
volume proper? YES
Clean oil cooler.
Is not oil cooler Secure air
clogged and is circulation route.
YES anything blocking YES
ⓐ
air circulation?
Is fan belt
NO tension proper?
Adjust belt
NO
tension or
replace belt.
Is not the set YES
pressure of main Readjust set
relief, relief and pressure.
ⓐ
travel relief valve Is main relief
lower than the YES
valve used very Reduce load.
standard level? NO often?

5-7
 3) CAVITATION OCCURS WITH PUMP

Cause Remedy
NO
Replenish
specified oil to
the standard
Is hydraulic oil level.
volume proper? YES
Replace oil with
one of proper
Is not viscosity viscosity.
of hydraulic oil
YES YES
too high? Clean suction
Is not suction strainer.
NO strainer clogged? Is not air intruding
from pump Check for air
NO intrusion in
suction line?
suction line and
retighten or
replace parts.

4) HYDRAULIC OIL IS CONTAMINATED

Cause Remedy
YES
Replace
Has not hydraulic hydraulic oil to be
oil passed specified.
specified replace-
ment hours? Has return filter
NO
been replaced at Flush with
NO
proper intervals? hydraulic oil and
replace return
filter.

5-8
4. SWING SYSTEM
1) BOTH LH AND RH SWING ACTIONS ARE IMPOSSIBLE

Cause Remedy
NO
Replenish
YES ⓐ
Is safety solenoid specified oil to the
YES
valve pressure standard level.
Is gear pump pilot within standard? Safety valve faulty Repair or replace.
NO
pressure within or not operated.
YES standard level?
Is oil in hydraulic
YES tank within
Gear pump faulty. Repair or replace.
standard level? NO
YES
Are broken pieces Pump connection Disassemble and
of coupling present coupling is broken. repair.
ⓐ when dust plug
under engine fly
Are attachment Is not main relief NO Hydraulic pump is Disassemble and
wheel is removed? NO
and travel valve faulty?
out of order. repair.
motions
impossible at all? NO
Does swing Swing control valve Disassemble and
YES control valve
spool is stuck. repair.
spool move
Is MCV pilot lightly by hand? ⓑ
YES YES
pressure within
standard level?
Does dozer ⓒ
NO
NO function?

Hydraulic pump is Disassemble and

NO
broken. repair.

YES
Swing brake Disassemble and
release valve is repair.
Is swing brake broken.
ⓑ release valve
faulty? YES
Swing reduction Disassemble and
Does swing unit is broken. repair.
NO motor rotate?
Swing motor is Disassemble and
NO
broken. repair.

YES
Pilot relief valve is Disassemble and
NO Is gear pump faulty. repair or replace.
delivering oil?
Gear pump is out Disassemble and
NO
Is gear pump pilot of order. repair.
ⓒ pressure within
standard level? YES
Is not there oil Clean pilot piping
leakage from interior or repair
YES pilot piping or is piping.
not it clogged?
Pilot valve is Disassemble and
NO
broken. repair.

5-9
 2) SWING SPEED IS LOW
Cause Remedy
YES
Swing port relief Disassemble and
Does swing control
YES valve is faulty. repair or replace.
valve spool move
smoothly by hand?
Swing control valve Disassemble
Is MCV pilot NO
spool is stuck. and repair.
pressure same
on LH and RH YES Clogged or oil
sides? Clean pilot piping
leak.
Is not pilot piping interior or repair
Single direction clogged or is not piping.
NO it leaking oil?
Is the trouble in Pilot valve or shuttle Disassemble
one direction or NO
valve is faulty. and repair.
in both direction? YES
ⓐ
Does swing
YES control valve
Both directions spool move
YES Is MCV pilot lightly by hand? Swing control valve Disassemble
pressure within NO
Is dozer speed spool is stuck. and repair.
standard level?
within standard ⓑ
value? NO
ⓒ
NO

Is swing motor's NO
ⓐ drain rate within Swing motor is Disassemble
standard value? Check that pilot broken. and repair.
piping is not
YES clogged or oil is NO
Pilot valve or Disassemble
not leaking from shuttle valve is and repair.
it? faulty.
Clogged or oil leak. Clean pilot piping
Is gear pump pilot interior or repair
ⓑ pressure within piping.
standard level?
YES
Pilot relief valve Disassemble and
Is gear pump is defective. repair or replace.
NO delivering oil?
Gear pump is Disassemble
NO
broken. and repair.

NO
Main relief valve Main relief valve
faulty. pressure resetting
or repair.

Is main relief Does the YES

ⓒ Hydraulic pump Disassemble
valve setting symptom change
YES
when LH and RH is broken. and repair.
pressure normal?
pilot hoses are
Is safety valve exchanged? Shuttle valve is Repair or replace.
NO
pilot pressure faulty.
YES within standard
YES
level? Is gear pump Pilot relief valve Repair or replace.
output pressure is faulty.
NO within standard
level? Gear pump is Repair or replace.
NO
faulty.

5-10
 3) SWING MOTION IS IMPOSSIBLE IN ONE DIRECTION

Cause Remedy
Does symptom YES
change when LH Swing port relief Disassemble
YES and RH port valve is faulty. and repair.
relief valves of
swing motor are
Shuttle valve is Disassemble
Does swing control exchanged NO
YES faulty. and repair.
valve spool move
smoothly by hand?

Is MCV pilot Swing control valve Disassemble

NO
pressure same spool is stuck. and repair.
for LH and RH?
Check if pilot NO
Pilot valve is faulty. Disassemble
piping is not
and repair.
clogged or does
NO
not have oil Clogged or oil
leakage. YES leak. Clean pilot piping
interior or repair
piping.

4) MACHINE SWINGS BUT DOES NOT STOP

Cause Remedy
YES
Pilot relief valve is Disassemble
faulty. and repair or
YES Is MCV pilot YES Is gear pump pilot
pressure within pressure within replace.
standard value? standard level?
Gear pump is Disassemble
NO
broken. and repair.
YES Does swing control
valve spool move
smoothly by hand? Pilot valve is faulty. Disassemble
NO
and repair.
Is swing control
valve's return
spring normal? Swing control Disassemble
NO
valve spool is and repair.
stuck.
Return spring is Disassemble
NO
faulty. and replace.

5-11
 5) THE SWING UNIT DRIFTS WHEN THE MACHINE IS AT REST ON A SLOPE

Cause Remedy
YES
ⓐ
YES Is swing shuttle
valve normal?
Shuttle valve is Disassemble
NO
faulty. and replace.
YES Is brake spring
normal?

Is return spring
of swing control Brake spring is Disassemble
NO
valve normal? faulty. and replace.

Return spring of Disassemble

NO
swing control and replace.
valve is faulty.

YES
Is drain rate of Swing relief valve Disassemble
YES swing motor is faulty. and repair or
within standard replace.
Is swing relief value? Swing motor is Disassemble
ⓐ NO
pressure within broken. and repair.
standard level?
Adjust swing
NO
relief valve
pressure or
replace swing
relief valve.

5-12
5. TRAVEL SYSTEM
1) TRAVEL DOES NOT FUNCTION AT ALL ON ONE SIDE

Cause Remedy
YES
Does counterbalance ⓐ
YES spool in travel
brake valve move
lightly by hand? Counter spool in Disassemble
Is travel brake NO
YES valve pressure travel brake valve and repair or
within standard is stuck. replace.
level? Does the symptom
change when
relief valves in YES
Relief valve built Disassemble
Has travel NO travel motor are
in travel motor is and repair.
YES control valve exchanged?
spool changed faulty.
over positively?
YES Control system is Disassemble
defective. inspect and
Does spool move repair.
NO lightly by hand?

Travel control Disassemble

NO
valve spool is and repair.
stuck.
Is bucket or arm
operation YES Disassemble
Travel reduction
possible? Do not metallic and repair.
unit is faulty.
particles come
ⓐ out of drain port
in travel
reduction unit? Travel motor is Disassemble
NO
out of order. and repair.
Does the symptom
NO
change when A1 YES
and A2 pump Hydraulic pump is Disassemble
Does the discharge hoses
symptom change broken. and repair.
are exchanged?
when LH/RH
NO
travel relief valves
are exchanged?
Travel relief Disassemble
YES
valves are faulty. and repair or
replace.

5-13
 2) SPEED ON ONE SIDE FALLS AND THE MACHINE CURVES

Cause Remedy
YES
Brake valve is Disassemble
Do LH and RH
travel speeds defective. and repair or
YES change when LH replace.
and RH travel YES
Does the symptom Relief valve built Disassemble
brake valves are change when in travel motor is and repair.
exchanged? relief valves in
faulty.
NO LH and RH
Has control valve travel motors are
YES
spool changed exchanged? ⓐ
over positively? NO
YES
Control system is Disassemble,
Does spool move faulty . inspect and
lightly when it is
Is the lower repair.
NO cut off from control
speed (bucket or spool?
arm) within Control valve Disassemble
standard level? NO
spool is stuck. and repair.

YES
Travel relief valve Disassemble
Do LH and RH
travel speeds is faulty. and repair or
change over when replace.
NO travel relief valves
are exchanged? Hydraulic pump is Disassemble
NO
broken. and repair.
Does travel speed
change when
YES parking brake YES
Travel motor's Disassemble
spring in the
slower travel parking brake is and clean pilot
Is leak rate of motor is removed? not released piping.
ⓐ travel motor within
standard level? properly.

Travel motor is Disassemble

NO
faulty. and repair.

5-14
 3) MACHINE DOES NOT STOP ON A SLOPE
Machine is pulled forward as sprocket rotates during digging operation.

Cause Remedy
None Is parking brake YES
friction plate Friction plate is Disassemble
YES Check if parking worn? faulty. and repair.
brake pilot line is
not clogged.
Clogged Disassemble
and clean pilot
Is drain rate of piping.
Is travel brake YES travel motor NO
pressure within within standard Travel motor is Disassemble
standard level? value? defective. and repair.
SPEC : 19 kgf/cm2

Brake valve is Disassemble

NO
faulty. and repair or
replace.

4) LH AND RH TRAVEL MOTIONS ARE IMPOSSIBLE

Cause Remedy
YES
Inspect according
to the procedure
"Travel does not
function at all on
one side."
However, a case
where both LH
and RH travel
motions are
disabled is
Is bucket or arm extremely seldom
operation
statistically.
possible? OK Hydraulic pump is Disassemble

Disassemble both faulty. and repair.

OK travel relief valves
Remove dust and inspect for
plug under engine any fault.
OK flywheel and Travel relief valve Disassemble
check that there is Faulty is faulty. and repair or
no coupling
replace.
element particles.
Check oil volume Particles present. Coupling at pump
in hydraulic oil connection is Disassemble
NO tank. broken. and repair.

Short Replenish
hydraulic oil.

5-15
 5) TRAVEL ACTION IS POWERLESS (travel only)

Cause Remedy
YES
ⓐ
Is travel motor's
YES drain rate within
standard level?
Is travel brake Travel motor is Disassemble
YES pressure within NO
faulty. and repair.
standard level?
Is travel relief
valve pressure Travel brake valve Disassemble
NO
within standard is defective. and repair or
level?
replace.
NO
Travel relief valve Disassemble
is faulty. and repair or
replace.

YES
Hydraulic circuit Disassemble
Does parking that releases and clean.
Increases brake piston travel parking
Remove parking move lightly by brake is clogged
brake spring in hand?
with dirt.
travel motor,
draw out piston Parking brake Disassemble
ⓐ NO
completely, refit piston in travel and repair.
cover and check motor is stuck.
if travel power
changes. Remains
unchanged Travel reduction Disassemble
unit is defective. and repair.

6) MACHINE RUNS RECKLESSLY ON A SLOPE

Cause Remedy
Travel brake valve
(counterbalance Disassemble
valve) is faulty. and repair or
replace.

5-16
 7) MACHINE MAKES A CURVED TRAVEL OR DOES NOT TRAVEL AT ALL WHEN TRAVEL
AND ATTACHMENT OPERATIONS ARE EXECUTED AT THE SAME TIME

Cause Remedy
YES
Normal.

YES Is select valve

normal?

Select valve is Repair or

Is travel lever NO
faulty. replace.
operate
normal? YES
Remove dirt on
Is filter in pilot pilot line filter.
piping between
gear pump and YES Is pilot relief NO
NO
control valve not Pilot relief valve is Disassemble
valve normal?
clogged? defective. and repair or
Is gear pump
replace.
NO delivering oil?

Gear pump is Disassemble

NO
broken. and repair.

5-17
6. ATTACHMENT SYSTEM
1) BOOM OR ARM ACTION IS IMPOSSIBLE AT ALL

Cause Remedy
YES
Does the Port relief valve is Disassemble
symptom change faulty. and repair or
YES
when port relief replace.
valve is replaced
Is MCV pilot with other valve? NO ⓐ
YES
pressure within
standard level? Inspect if pilot
piping is not
OK
clogged or oil is Pilot valve is Disassemble
Are other NO
not leaking from faulty. and repair.
YES attachments
the piping.
operatable?
YES
Pilot relief valve is Disassemble
Is gear pump
pilot pressure YES Is gear pump faulty. and repair or
NO within standard delivering oil? replace.
level? Gear pump is Disassemble
NO
zzzz broken. and repair.
Are LH/RH travel
operations OK
possible? Hydraulic pump is Disassemble
Disassemble broken. and repair.
NO main relief valve
Remove dust plug and check if it is
under engine not irregular.
OK flywheel and
Main relief valveDisassemble
Faulty
check if coupling is defective. and repair or
element particles replace.
Inspect oil are not present. Particles present Coupling at pump Disassemble
volume in
NO connection is and repair.
hydraulic oil tank. YES
broken.
Short Replenish
hydraulic oil.

YES
Cylinder interior is Disassemble
Does control broken. and repair.
ⓐ valve spool move
lightly by hand?
Control valve Disassemble
NO
spool is stuck. and repair.

5-18
 2) BOOM, ARM OR BUCKET SPEED IS LOW
Cause Remedy
YES
Normal.
YES
Are other ⓐ
YES attachment
Is combination speeds within
Is speed low only of oil streams standard levels? NO ⓑ
in composite YES
normal at boom YES
operation? hoisting and at Does spool of flow Flow summation Disassemble and
arm extrusion? summation check check valve spool repair.
NO valve move lightly is stuck.
Are LH/RH travel by hand?
NO speeds within NO
standard levels?
YES
Hydraulic pump is Disassemble and
Are both LH/RH faulty. repair.
travel speeds YES ⓒ
NO
low? Is MCV pilot
pressure within
NO
standard? ⓓ
NO
OK
Does the Port relief valve is Disassemble and
symptom change faulty. repair or replace.
YES
when port relief
valve is replaced
Does control with other valve? Cylinder is faulty. Disassemble and
YES valve spool move NO
repair.
lightly by hand?
Control valve spool Disassemble and
Is MCV pilot NO
ⓐ pressure within is stuck. repair.
standard level?
YES Clean pilot piping
Is not MCV pilot
pressure piping interior or repair
NO clogged or is not piping.
there oil leakage? Pilot valve is Disassemble and
NO
defective. repair.
YES
Pilot relief valve is Disassemble and
Is primary pilot NO Is gear pump faulty. repair or replace.
ⓑ pressure within delivering oil?
standard level?
Gear pump is Disassemble and
NO
broken. repair.
Is engine NO
ⓒ revolution within Adjust engine
standard level? revolution.

YES
Clean orifice in
control valve.
Is not orifice in
ⓓ control valve YES
clogged? Is pilot piping not Clean pilot piping
clogged or is oil interior or repair
NO not leaking from piping.
the piping? Is pilot valve
Pilot valve is faulty. Disassemble and
NO normal? NO
repair.

5-19
 3) BOOM, ARM OR BUCKET CYLINDER EXTENDS OR CONTRACTS ITSELF AND
ATTACHMENT FALLS

Cause Remedy
YES
Port relief valve is Disassemble
Does the symptom faulty. and repair or
change when port
Normal replace.
relief valve is YES
replaced with ⓐ
normal valve? Is control valve
Is not hydraulic return spring
YES NO
oil temperature normal?
Control valve's Disassemble
high? NO
return spring is and replace.
faulty.
Is genuine Abnormally high. Locate the cause
hydraulic oil or of hydraulic oil
equivalent being temperature rise
used?
and lower it to
proper level.

Replace with
NO
genuine
hydraulic oil or
equivalent.

OK
Pressure Disassemble
Disassemble and tightness and repair.
inspect check between control
YES
valve in hydraulic
circuit and check valve casing and
for any fault. spool is poor.
Is cylinder internal Abnormal Contact surface Disassemble
ⓐ leakage within between poppet and repair.
standard level?
and seat is poor.

Cylinder is faulty. Disassemble

NO
and repair.

5-20
 4) BOOM, ARM OR BUCKET POWER IS WEAK

Cause Remedy
YES
Check according
Is cylinder to the procedure
YES internal leakage in Item "Speed is
within standard low".
Is relief pressure level?
YES in port relief Cylinder is faulty. Disassemble
valve within NO
standard level? and repair.
Is relief pressure
in main relief Port relief valve is Adjust pressure,
valve within NO
standard level? faulty. repair or replace.

Main relief valve Adjust pressure,

NO
is defective. repair or replace.

5) ONLY BUCKET OPERATION IS TOTALLY IMPOSSIBLE

Cause Remedy
YES
Port relief valve is Disassemble
Does the
symptom change defective. and repair or
YES
when port relief replace.
YES
valve is replaced Does control Cylinder interior is Disassemble
with other valve? valve spool move broken. and repair.
Is MCV pilot NO smoothly by
pressure within hand?
standard level? NO Control valve Disassemble
spool is stuck. and repair.

NO Pilot valve is Disassemble

faulty. and repair.

5-21
 6) BOOM MAKES A SQUEAKING NOISE WHEN BOOM IS OPERATED

Cause Remedy
YES
Frictional noise
occurs between
the sliding faces
of boom
cylinder's oil
Is boom foot pin seal and boom
greased proper.
sufficiently?
※ Frictional
noise will
disappear if
they are kept
used.

Boom foot pin Supply grease

NO
has run out of to it.
grease. ※
If seizure is in
an initial stage,
supply sufficient
grease.
If seizure is in
a grown state,
correct it by
paper lapping
or with an oil
stone.

5-22
※ HOW TO CHECK INTERNAL BOOM CYLINDER LEAKAGE
1. Lower the bucket teeth to the ground with
bucket cylinder fully retracted and arm
cylinder rod retracted almost in full.

R27Z96MA02

2. Disconnect hose (A) from rod side of boom

cylinder and drain oil from cylinders and
hose. (Put cups on piping and hose ends)

R5575BY02

3. Raise bucket OFF the ground by retracting

the arm cylinder rod.

If oil leaks from piping side and boom

cylinder rod is retracted there is an internal
leak in the cylinder.
If no oil leaks from piping side and boom
cylinder rod is retracted, there is an internal
leak in the control valve.
R35Z75TS02

5-23
 GROUP 3 ELECTRICAL SYSTEM

1. WHEN STARTING SWITCH IS TURNED ON, MONITOR PANEL DISPLAY DOES NOT
APPEAR
·Before disconnecting the connector, always turn the starting switch OFF.
·Before carrying out below procedure, check all the related connectors are properly inserted and
short of fuse No. 7.
·After checking, insert the disconnected connectors again immediately unless otherwise specified.

Cause Remedy
YES
Defective cluster Replace

Check voltage YES

between CN-56 Disconnection in Repair or
(25) and chassis wiring harness or replace
Check voltage poor contact (after clean)
Starting switch : ON
Voltage : 10~12.5V between CN-4 between CN-56
NO (3) and chassis
(25) and CN-4 (3)
Voltage : 10~12.5V
Disconnection in Repair or
NO
wiring harness or replace
poor contact (after clean)
between CN-4 (3)
and fuse No.7

Check voltage
YES 10 ~ 12.5V
NO 0V

CLUSTER 1 1
POWER IG(12V) 25 3 3
CN-56 8 8
FUSE
15 15
CN-4 CN-2 NO.7

R25Z9AK5TS02

5-24
 2. BATTERY CHARGING WARNING LAMP LIGHTS UP (starting switch : ON)

·Before disconnecting the connector, always turn the starting switch OFF.
·Before carrying out below procedure, check all the related connectors are properly inserted.
·After checking, insert the disconnected connectors again immediately unless otherwise specified.

Cause Remedy
YES
Defective cluster Replace
YES Check voltage
between CN-56
(7) and chassis Disconnection in Repair or replace
NO
wiring harness or (after clean)
YES Check voltage poor contact
between CN-5
(13) and chassis between CN-56
(7)-CN-5 (13)
Check voltage Disconnection in Repair or replace
between alternator NO wiring harness or (after clean)
terminal CN-74 (1) poor contact
and chassis between CN-5 (13)
-alternator terminal
Voltage : 10~12.5V
CN-74 (1)
Engine : Running
Defective alternator Replace
NO

Check voltage
YES 10 ~ 12.5V
NO 0V

CLUSTER ALTERNATOR
B+
G
7 13 1 L
3~
2 IG
U
CN-56 CN-5 3 P
CN-74

17Z9A5TS03

5-25
3. WHEN COOLANT OVERHEAT WARNING LAMP LIGHTS UP (Engine is started)

·Before disconnecting the connector, always turn the starting switch OFF.
·Before carrying out below procedure, check all the related connectors are properly inserted.
·After checking, insert the disconnected connectors again immediately unless otherwise specified.

Cause Remedy
YES
Coolant overheat Check engine
Check resistance (115˚C ±2˚C ) cooling system
YES between
or replace temp
overheat switch switch
and chassis?
Disconnect CD-9
Does display go Yes≤0~1.1Ω
NO Defective overheat Repair or replace
off when No = ∞Ω
switch the detector
disconnect CD-9?
Starting switch : ON YES
Engine : Start Short circuit in Repair or replace
Check resistance wiring harness (after clean)
between CN-56
NO (2) and chassis?
Defective cluster Replace
Disconnect CN-56
NO
Yes≤0~1.1Ω
No = ∞Ω

CLUSTER OVERHEAT SWITCH

T
2 3
CD-9

CN-56 CN-5

17Z9A5TS04

5-26
4. WHEN ENGINE OIL PRESSURE WARNING LAMP LIGHTS UP (Engine is started)

·Before disconnecting the connector, always turn the starting switch OFF.
·Before carrying out below procedure, check all the related connectors are properly inserted.
·After checking, insert the disconnected connectors again immediately unless otherwise specified.

Cause Remedy
YES
Engine oil leakage, Check engine oil
or defective switch level or replace
Does display go off switch
when disconnect
YES
CD-18? Defective cluster Replace
Starting switch : ON Check resistance
Engine : Start between CN-56
NO
(3) and chassis
Starting switch : OFF
Disconnection in Repair or replace
NO
Disconnect CN-56 wiring harness or (after clean)
poor contact
between
CN-56 (3)-CD-18

Check resistance
YES MAX 1Ω
NO MIN 1MΩ

CLUSTER ENGINE OIL PRESSURE SWITCH

3 1 Pa

CN-56 CN-5 CD-18

1695TS06

5-27
5. WHEN AIR CLEANER WARNING LAMP LIGHTS UP (Engine is started)

·Before disconnecting the connector, always turn the starting switch OFF.
·Before carrying out below procedure, check all the related connectors are properly inserted.
·After checking, insert the disconnected connectors again immediately unless otherwise specified.

Cause Remedy
YES
Clogged air filter or Check filter or
Check resistance
YES between air defective switch replace switch
cleaner switch
and chassis?
Does display go Disconnect CD-10
off when Yes≤0~1.1Ω Defective the Repair or replace
No = ∞Ω NO
disconnect CD-10 detector the detector
and CN-56 (4)?
Starting switch : ON YES
Engine : Start Short circuit in Repair or replace
Check resistance wiring harness (after clean)
between CN-56
NO
(4) and chassis?
Defective cluster Replace
Disconnect CN-56
NO
Yes≤0~1.1Ω
No = ∞Ω

Check resistance
YES MAX 1Ω
NO MIN 1MΩ

CLUSTER
AIR CLEANER
PRESSURE SWITCH
4 4
Pa

CD-10
CN-56 CN-5

R25Z9AK5TS13

5-28
6. WHEN COOLANT TEMPERATURE GAUGE DOES NOT OPERATE

·Before disconnecting the connector, always turn the starting switch OFF.
·Before carrying out below procedure, check all the related connectors are properly inserted.
·After checking, insert the disconnected connectors again immediately unless otherwise specified.

Cause Remedy
YES
Disconnection in Repair or replace
wiring harness or (after clean)
Is resistance poor contact
YES between CN-56
between
(17) and chassis CN-56-CD-8
over 2kΩ?
Starting switch : OFF YES
Disconnect CN-50 Defective cluster Replace
Does the gauge
move up and Check resistance
down at lamp NO
between CN-5
check? (9) and chassis
Defective temp Replace
See Table NO
Starting switch : ON sensor

Defective cluster Replace

NO

Check Table
Red
range Temperature 115˚C
50˚C 80˚C 100˚C
Item (red range)
Unit resistance (Ω) 350 118 63.5 42

CLUSTER
WATER TEMP SENSOR
17 9 C

CD-8
CN-56 CN-5

R25Z9AK5TS07

5-29
7. WHEN FUEL GAUGE DOES NOT OPERATE (Check warning lamp ON/OFF)

·Before disconnecting the connector, always turn the starting switch OFF.
·Before carrying out below procedure, check all the related connectors are properly inserted.
·After checking, insert the disconnected connectors again immediately unless otherwise specified.

Cause Remedy
YES
Disconnection in Check and repair
wiring harness
Is resistance
YES between CN-56
(18) and chassis
over 1kΩ? YES
Defective cluster Replace
Starting switch : OFF
Disconnect CN-51
Check resistance
Does the gauge between CD-2
move up and NO (2) and chassis
down at lamp Defective fuel Replace
Disconnect CD-2 NO
check? sender
See Table
Starting switch : ON

Defective cluster Replace

NO

Check Table
Temperature
Empty 1/2 Full
Item
Unit resistance (Ω) 100 37 5

Red range

CLUSTER
FUEL SENDER
1 2 3

18 5 2
3 1
CD-2
CN-56 CN-5

17Z9A5TS08

5-30
8. WHEN SAFETY SOLENOID DOES NOT OPERATE

·Before disconnecting the connector, always turn the starting switch OFF.
·Before carrying out below procedure, check all the related connectors are properly inserted and
short of fuse No.10.
·After checking, insert the disconnected connectors again immediately unless otherwise specified.

Cause Remedy
YES
Hydraulic Check hydraulic
YES Check operation malfunction system
of solenoid
Defective solenoid Replace
NO
Safety lever : ON-OFF YES
Defective switch Repair or replace
(CS-4)
YES Check voltage
between CS-4
Check voltage (2) and chassis
between CN-68 Disconnect in Repair or replace
Check voltage Starting switch : ON NO
(1) - (2) YES Voltage : 10~12.5V wiring harness or (after clean)
between CN-3 Disconnect CS-4 poor contact
Starting switch : ON (12) and chassis
Voltage : 10~12.5V between
Safety state Starting switch : ON CN-3 (12)-CS-4 (2)
Voltage : 10~12.5V
Check voltage Disconnect CN-3 Disconnect in Repair or replace
between CN-68 NO (after clean)
wiring harness or
NO (2) with chassis
poor contact
Safety lever : OFF between
Starting switch : ON CN-3 (12)-CN-68
Voltage : 10~12.5V
(2)

Disconnection in Repair or replace

NO
wiring harness
between
CN-68 (2)-fuse

FUSE
13
NO.10

CN-2
SAFETY SWITCH
SAFETY SOLENOID
2 11 1
1 12 2
CS-4 CN-68
CN-3

R25Z9AK5TS20

5-31
9. WHEN TRAVEL SPEED 1, 2 DOES NOT OPERATE

·Before disconnecting the connector, always turn the starting switch OFF.
·Before carrying out below procedure, check all the related connectors are properly inserted and
short of fuse No.8.
·After checking, insert the disconnected connectors again immediately unless otherwise specified.

Cause Remedy
YES
Defective hydraulic Check hydraulic
system system
YES Check voltage YES Check operation
between CS-8 YES
of solenoid Defective cluster Replace
and chassis
Check if travel Check resistance
Starting switch : ON Starting switch : ON between CN-70
speed lamps( , Voltage : 10~12.5V : OFF NO
) change when : ON
(1) and (2)
pressing the travel Starting switch : OFF NO Defective solenoid Replace
speed switch SPEC : 15~25Ω
Disconnect CN-70
Starting switch : ON
Defective switch Replace
NO

FUSE
4
NO.8
CN-2

TRAVEL SPEED SW
TRAVEL SOLENOID
1
2
CN-70
CS-8

R30Z9AK5TS21

5-32
10. WHEN STARTING SWITCH IS TURNED ON, WIPER MOTOR DOES NOT OPERATE

·Before disconnecting the connector, always turn the starting switch OFF.
·Before carrying out below procedure, check all the related connectors are properly inserted and the
fuse No.7 is not blown out.
·After checking, insert the disconnected connectors again immediately unless otherwise specified.

Cause Remedy
NO
Recheck fuse Replace

Check voltage NO
between CS-3(1) Defective wiper Replace
and chassis switch

Voltage : 10~12.5V Check voltage

between CS-3
YES (6) and chassis YES
Defective wiper Replace
Wiper switch : ON Check voltage motor
Voltage : 10~12.5V between CN-21
YES (3) and chassis
Recheck fuse Replace
Starting switch : ON NO
Voltage : 10~12.5V

WASHER P/P
M 2 3
1
CN-22
CN-3

CN-2
FUSE CN-4-1 WIPER & WASHER SW
15 1 1
I 0

NO.7 2
3 3
0, I

4
WIPER MOTOR 4 5
1
6 6
2 E 1 8
1 Pf 2 7
3 B 3 8 3
4 9
10 10 9
M 4 Lo
CS-3
CN-21
R30Z9AK5TS14

5-33
11. WHEN STARTING SWITCH IS TURNED ON, HEAD LAMP DOES NOT LIGHTS UP

·Before disconnecting the connector, always turn the starting switch OFF.
·Before carrying out below procedure, check all the related connectors are properly inserted and
short of fuse No.6.
·After checking, insert the disconnected connectors again immediately unless otherwise specified.

Cause Remedy
NO
Defective lamp Replace switch
switch

YES Check voltage

between CS-21 YES
(1) and (5) Defective bulb Replace
Check voltage
YES between CL-9 (1)
Starting switch : ON / CL-10 (1) and
Head lamp switch : ON
Voltage : 10~12.5V
chassis Disconnection in Repair or replace
Starting switch : ON NO
wiring harness or (after clean)
Check voltage Head lamp switch : ON
between CN-3 Voltage : 10~12.5V poor contact
YES (2) and chassis between CN-3 (2)
Check voltage -CL-9 (1)/10 (1)
Starting switch : ON
between CS-21 Head lamp switch : ON
(1) and chassis Voltage : 10~12.5V
Disconnection in Repair or replace
NO
Starting switch : ON wiring harness or (after clean)
Head lamp switch :
ON-OFF poor contact
between
CS-21 (5)-CN-3 (2)

Disconnection in Repair or replace

NO
wiring harness or (after clean)
poor contact
between CS-21
(5) and fuse

HEAD LAMP
1
2
CL-9
LIGHT SW
1
10
9 10 1
9
4 8
2 2
2 CL-10
7
CN-10
7 1 6
5 5 2
4 FUSE
3 8 6
I 0

2 NO.6
1 CN-3 CN-2
CS-21
R30Z9AK5TS15

5-34
12. WHEN STARTING SWITCH IS TURNED ON, WORK LAMP DOES NOT LIGHTS UP

·Before disconnecting the connector, always turn the starting switch OFF.
·Before carrying out below procedure, check all the related connectors are properly inserted and
short of fuse No.5.
·After checking, insert the disconnected connectors again immediately unless otherwise specified.

Cause Remedy
NO
Defective lamp Replace switch
switch

YES
Check voltage Defective bulb Replace
YES
between CS-21 YES Check voltage
(4) and (2) between CL-5
(2) and chassis
Starting switch : ON Disconnection in Repair or replace
Work lamp switch : ON Starting switch : ON NO
wiring harness or (after clean)
Voltage : 10~12.5V Work lamp switch : ON
Check voltage Voltage : 10~12.5V poor contact
between CN-3 between CN-3
YES (14) and chassis
(14) and CL-5 (2)
Starting switch : ON
Check voltage Work lamp switch : ON
between CS-21 Voltage : 10~12.5V
(4) and chassis Disconnection in Repair or replace
NO
Starting switch : ON wiring harness or (after clean)
Work lamp switch :
ON-OFF
poor contact
Voltage : 10~12.5V between
CS-21 (2)-CN-3
(14)

Disconnection in Repair or replace

NO
wiring harness or (after clean)
poor contact
between CS-21
(4) and fuse

LIGHT SW
9 10 10
9
4 8
2 WORK LAMP
7
1
7 1 6
5 2
5
4
CL-5
3
I 0

2 14
1 FUSE
CS-21 13 10
NO.5
CN-3
CN-2
R25Z9AK5TS12

5-35
13. WHEN ENGINE DOES NOT START R
R

FUSE BOX START RELAY START SW

·Before disconnecting the connector, always turn the starting switch OFF. (R1) (BR) (ACC) (R2) (C)

12
11
10

85

86
2

7
6

9
1

B1
B4
B2
B3
A2
H0 I
·Before carrying out below procedure, check all the related connectors are properly inserted.

20A

10A

10A

10A

20A

20A

30A

20A

20A

10A

10A

20A

87

30
CR-23
·After checking, insert the disconnected connectors again immediately unless otherwise specified. A

86
85

30
87
POWER OUTLET, EPPR
GLOW TIMER

MONITOR,WIPER MOTOR
START
HORN, BEACON
WORK LAMP

HEAD LAMP

TRAVEL,QUICK SOL.

SAFETY SOL.
0, I

FUEL FEED, ALT

HEATER
B+

A1
(B)

A B

CS-46
W
R

CS-2
G

1
2

4
1

2
3
G
L
R
R
CN-36
2
Cause Remedy
YES Repair or replace
Defective timer
YES Check voltage
Timer
between CR-24
(4) and chassis Disconnection in
NO
Repair or replace
Starting switch : ON wiring harness or fuel cut off relay or
poor contact repair or replace

W
R
CN-145
between CR-24 (after clean) FEED PUMP

CN-2

CN-1
Check operation 1 M
(4) and fuse box

15
14
13
12
11
10

2
1
7
6
3

2
1
9
8
of start motor Check voltage 2
YES between starter YES

W
R
Defective magnet Repair or replace
Starting switch : START
magnet coil and of start motor start motor
chassis
Voltage : 10~12.5V Defective start Repair or replace
Check operation NO relay start relay

4
5
2

6
3
CN-80
NO of start relay R
Check voltage

GLOW POWER

GLOW LAMP -
Starting switch : START YES

KEY START
between start Defective start Repair or replace AIR-HEATER
NO relay (86) and

CR-24
relay start relay

GND
CN-74
chassis

NC
NC
R
B+
G
GLOW TIMER RY
Voltage : 10~12.5V Disconnection in Repair or replace 1 L
3 ~
NO 2 IG
wiring harness or (after clean) 3 P
U

poor contact ALTERNATOR

between CR-23 3
(86)and CS-46 (1) W
CN-45
R
B+
M
W
S
STARTER
4 CS-74

R B
W

MASTER SW BATTERY
1 (12V)
CN-60
W
2
R
1

FUSIBLE LINK

CN-5

CN-4
13

13
15
14

15
14
7

3
6
1

2
1
CN-56

21
22
23
24
25
26
27
10
11
12
13
14
15
16
17

28

30
18

20
19

29

31
32
33
1

4
5

34

36
2

6
7
8
9

35
3
W
R
L

ENGINE PREHEAT
CR-35

COOLANT TEMP
SAFETY LEVER

ANTI-RESTART
ENGINE OIL PS

PROGRAM D/N
86
30
85

87

QUICK CLAMP

ALTERNATOR

CLUSTER-RX
CLUSTER-TX
AIRCLEANER

FUEL LEVEL
OVERLOAD
OVERHEAT
70A

1/2 SPEED

BATTERY
BUZZER
TACHO
87

30

GND
GND
IGN
85

86

-
-
-
-

-
-

-
-
-
-
-
-
-
-
POWER RELAY CLUSTER

R27Z9AK4EL05

5-36
14. WHEN STARTING SWITCH ON DOES NOT OPERATE
R

·Before disconnecting the connector, always turn the starting switch OFF. R

FUSE BOX START RELAY START SW

·Before carrying out below procedure, check all the related connectors are properly inserted and (R1) (BR) (ACC) (R2) (C)

12
11
10

85

86
2

7
6

9
1

B1
B4
B2
B3
A2
H0 I

20A

10A

10A

10A

20A

20A

30A

20A

20A

10A

10A

20A
master switch ON.

87

30
CR-23
A
·After checking, insert the disconnected connectors again immediately unless otherwise specified.

86
85

30
87
POWER OUTLET, EPPR
GLOW TIMER

MONITOR,WIPER MOTOR
START
HORN, BEACON
WORK LAMP

HEAD LAMP

TRAVEL,QUICK SOL.

SAFETY SOL.
0, I

FUEL FEED, ALT

HEATER
B+

A1
(B)

A B

CS-46
W
R

CS-2
G

1
2

4
1

2
3
Cause Remedy

G
L
R
R
CN-36
YES 2
Defective start Replace
YES Check voltage switch
between CS-2
(1) and chassis
Disconnection in Replace
Voltage : 10~12.5V NO
wiring harness or
Check voltage
and specific poor contact

W
R
CN-145 FEED PUMP
gravity of battery between CS-2

CN-2

CN-1
1 M

15
14
13
12
11
10

2
1
7
6
3

2
1
9
8
Specific gravity : MIN 1.28 (1)-Starter 2
Voltage : MIN 10V

W
R
Battery capacity Charge or
NO
too low replace
(after clean)

4
5
2

6
3
CN-80

GLOW POWER

GLOW LAMP -
KEY START
AIR-HEATER

CR-24

GND
CN-74

NC
NC
R
B+
G
GLOW TIMER RY 1
2
L
IG
3 ~
U
3 P

ALTERNATOR
3
W
CN-45
R
B+
M
W
S
STARTER
4 CS-74

R B
W

MASTER SW BATTERY
1 (12V)
CN-60
W
2
R
1

FUSIBLE LINK

CN-5

CN-4
13

13
15
14

15
14
7

3
6
1

2
1
CN-56

21
22
23
24
25
26
27
10
11
12
13
14
15
16
17

28

30
18

20
19

29

31
32
33
1

4
5

34

36
2

6
7
8
9

35
3
W
R
L

ENGINE PREHEAT
CR-35

COOLANT TEMP
SAFETY LEVER

ANTI-RESTART
ENGINE OIL PS

PROGRAM D/N
86
30
85

87

QUICK CLAMP

ALTERNATOR

CLUSTER-RX
CLUSTER-TX
AIRCLEANER

FUEL LEVEL
OVERLOAD
OVERHEAT
70A

1/2 SPEED

BATTERY
BUZZER
TACHO
87

30

GND
GND
IGN
85

86

-
-
-
-

-
-

-
-
-
-
-
-
-
-
POWER RELAY CLUSTER

R27Z9AK4EL05

5-37