POWER TRIM

5
C

26345

PRESTOLITE POWER TRIM PUMP

Table of Contents
Page Page
Identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5C-1 Trim Pump Removal . . . . . . . . . . . . . . . . . . . . . 5C-13
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5C-1 Hydraulic Repair . . . . . . . . . . . . . . . . . . . . . . . . 5C-13
Valve Pressure Specifications . . . . . . . . . . . 5C-1 Manual Release Valve Replacement . . . . 5C-13
Electrical Specifications . . . . . . . . . . . . . . . . 5C-1 Disassembly . . . . . . . . . . . . . . . . . . . . . . . . . 5C-13
Lubricants/Sealers/Adhesives . . . . . . . . . . . . . . 5C-1 Valve Body and Gear Assembly . . . . . . . . 5C-14
Special Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5C-1 Motor Repair . . . . . . . . . . . . . . . . . . . . . . . . . . . 5C-15
Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5C-2 Disassembly . . . . . . . . . . . . . . . . . . . . . . . . . 5C-15
Thermal Circuit Breaker Operation . . . . . . . . . 5C-2 Armature Tests . . . . . . . . . . . . . . . . . . . . . . . 5C-17
Manual Release Valve Operation . . . . . . . . . . . 5C-2 Continuity Test . . . . . . . . . . . . . . . . . . . . . 5C-17
Maintaining Power Trim Pump Oil Level . . . . . 5C-2 Test For Shorts . . . . . . . . . . . . . . . . . . . . 5C-17
Air Bleeding Power Trim System . . . . . . . . . . . 5C-3 Cleaning Commutator . . . . . . . . . . . . . . 5C-17
Bleeding OUT/UP Trim Circuit . . . . . . . . . . . 5C-3 Field Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5C-17
Bleeding IN/DOWN Trim Circuit . . . . . . . . . 5C-3 Test For Open Circuit . . . . . . . . . . . . . . . 5C-17
Testing Power Trim Pump . . . . . . . . . . . . . . . . . 5C-4 Test For Short In Field . . . . . . . . . . . . . . 5C-18
Connecting Test Gauge . . . . . . . . . . . . . . . . 5C-4 Thermal Switch Test . . . . . . . . . . . . . . . . . . 5C-18
Internal Restriction Test . . . . . . . . . . . . . . . . 5C-5 Continuity Test . . . . . . . . . . . . . . . . . . . . . 5C-18
OUT/UP Pressure Test . . . . . . . . . . . . . . . . . 5C-5 Brush Lead Tests . . . . . . . . . . . . . . . . . . . . . 5C-18
IN/DOWN Pressure Test . . . . . . . . . . . . . . . . 5C-5 Brush Replacement . . . . . . . . . . . . . . . . . . . 5C-19
Trim Cylinder Internal Leak Test . . . . . . . . . . . . 5C-5 Brush Replacement . . . . . . . . . . . . . . . . 5C-19
Trim Cylinder Shock Piston Test . . . . . . . . . . . . 5C-7 End Cap And Brush Assembly
Motor and Electrical Bench Tests . . . . . . . . . . . 5C-7 Replacement . . . . . . . . . . . . . . . . . . . . . 5C-19
Trim Pump Motor Test (In Boat) . . . . . . . . . 5C-7 Reassembly . . . . . . . . . . . . . . . . . . . . . . . . . 5C-20
Trim Pump Motor Test (Out of Boat) . . . . . . 5C-8 Trim Pump Installation . . . . . . . . . . . . . . . . . . . 5C-22
Solenoid Test (Pump in Boat) . . . . . . . . . . . 5C-9 Wiring Diagram . . . . . . . . . . . . . . . . . . . . . . . . . 5C-23
Solenoid Test (Pump Out of Boat) . . . . . . . 5C-10
110 Amp Fuse Test (Pump in Boat) . . . . . 5C-11
110 Amp Fuse Test
(Pump Out of Boat) . . . . . . . . . . . . . . . . . . 5C-12
20 Amp Fuse Test . . . . . . . . . . . . . . . . . . . . 5C-12

5C-0 – PRESTOLITE POWER TRIM PUMP 90-12934--2 1097

Identification Specifications
Some MerCruiser Sterndrives will be equipped with
a Prestolite Power Trim pump. This pump was used Valve Pressure Specifications
interchangeably with the Oildyne pump for a period
of time. Valve Pressure
2200 - 2600 PSl
Up Circuit
(15173 - 17932 kPa)
400 - 600 PSl
Down Circuit
(2759 - 4138 kPa)

Electrical Specifications
115 Amps at
Pump Amperage Draw 2200 - 2600 PSl
(15173 - 17932 kPa)

Lubricants/Sealers/
Adhesives
Description Part No.
Power Trim and Steering
92-90100A12
Fluid
2-4-C Marine Lubricant 92-825407A2
Liquid Neoprene 92-25711-2
50524

Prestolite Power Trim Pump Special Tools

Description Part No.
Test Gauge Kit 91-52915A6
Multi-Meter 91-99750
Torque Wrench (lb. ft.) 91-36210
Torque Wrench (lb. in.) 91-66274
Jumper Wire Obtain Locally

90-12934--2 1097 PRESTOLITE POWER TRIM PUMP - 5C-1

Description Maintaining Power Trim
The Prestolite Power Trim Pump has internal valving Pump Oil Level
that eliminates the need for an external reverse lock,
as was required in the past. The pump generates a ! CAUTION
higher volume of fluid, but at a lower pressure than
previous Prestolite pumps. This, in conjunction with Vent screw MUST BE backed out two (2) full turns
large I.D. hydraulic hoses (gimbal housing to pump) (after bottoming out) to vent pump reservoir.
and larger I.D. trim cylinders, should allow the drive FAILURE TO BACK SCREW OUT COULD RE-
unit to “kick-up” easier if an underwater object is SULT IN DAMAGE TO PUMP.
struck.
IMPORTANT: Check oil level with sterndrive unit
! CAUTION in the full down position.
Due to differences in internal valving, the new IMPORTANT: SAE 10W-30 or 10W-40 engine oil
Prestolite trim pump cannot be used to replace can be used in system, if Quicksilver Power Trim
an earlier Prestolite pump, or vice-versa. Use of and Steering Fluid is not available.
incorrect pump will affect trim operation and may 1. Place drive unit in the full IN/DOWN position.
cause damage to trim system.
2. Remove “Fill” screw from pump. Oil level should
The pump motor is protected from overheating by an be up to bottom of the threads in “Fill” screw hole.
internal circuit breaker (on commutator end plate), If necessary, add Quicksilver Power Trim and
that interrupts the current flow through the field wind- Steering Fluid or SAE 10W-30 or 10W-40 motor
ings in the event of an overheating condition. Electri- oil (through “Fill” screw hole).
cal current overload protection is provided to the
pump by a 110 amp fuse. Pump also is fitted with a NOTE: In tropical areas, single viscosity SAE 30 mo-
20 amp in-line fuse, which serves to protect the trim tor oil can be used.
control and harness from an overload.

Thermal Circuit Breaker

Operation
If the IN/DOWN or “Trailer” switch is kept depressed
after drive unit reaches its end of travel, a thermal
circuit breaker will open to prevent pump motor from
overheating and pump motor will stop. Release
switch(es) as soon as drive unit reaches end of
travel, to prevent this from happening. If circuit
breaker should open, allow motor to cool down and
circuit breaker will automatically reset.

Manual Release Valve

Operation
! WARNING
Before loosening manual release valve, make
sure all persons are clear of sterndrive unit.
50524
In case of a Power Trim system malfunction, the
sterndrive unit can be raised and lowered manually a - Fill Screw
by turning the manual release valve b - Vent Screw
c - Manual Release Valve
counterclockwise approximately 3 turns and moving
drive unit to desired position by hand. After drive unit
has been placed in the desired position, close valve 3. Raise and lower drive unit 6 to 10 times to purge
COMPLETELY. Power Trim system will not function any air from system; then, recheck oil level (with
properly, unless valve is completely closed. drive unit fully IN/DOWN) and add oil if
necessary.

5C-2 – PRESTOLITE POWER TRIM PUMP 90-12934--2 1097

Air Bleeding Power Trim Bleeding IN/DOWN Trim Circuit
System 1. Ensure pump reservoir is filled to proper level.
The power Trim System will purge itself of a small 2. Disconnect IN/DOWN hose from rear connection
amount of air by raising and lowering the drive unit on gimbal housing hydraulic connector. If both
several times. However, if a rebuilt trim cylinder is cylinders were rebuilt, disconnect hoses from
being installed (which has not been filled with oil), the both sides of hydraulic connector.
following bleeding procedure should be used to 3. Plug holes in hydraulic connector, using plug
remove the air from the system. (22-38609) or suitable device.
4. Direct end of trim hose(s) into container.
Bleeding OUT/UP Trim Circuit
5. Run trim pump in the UP direction until trim cylin-
1. Fill pump reservoir to proper level as explained ders are fully extended.
preceding. (Trim cylinder must be compressed).
6. Remove plug(s) from gimbal housing hydraulic
2. Disconnect OUT/UP hose from front connection connector and momentarily run trim pump in the
on trim cylinder. If both cylinders were rebuilt, dis- IN/DOWN direction until a solid, air-free stream
connect hoses from both cylinders. of fluid is expelled from rear hole(s) in hydraulic
3. Direct end of trim hose(s) into a container. connector. Reconnect trim hose(s) and tighten
securely.
4. Run trim pump in the UP direction until a solid, air-
free stream of fluid is expelled from hose(s). Re- 7. Lower drive unit to the full IN/DOWN position and
connect hose(s) and tighten securely. refill trim pump to proper level. Run trim system
IN/DOWN and OUT/UP several times and re-
5. Refill trim pump to proper level. check fluid level.

22089
22089 a - IN/DOWN Trim Hose
a - OUT/UP Trim Hose b - Hydraulic Connector
b - Front Connection on Trim Cylinder c - Plug (22-38609)

90-12934--2 1097 PRESTOLITE POWER TRIM PUMP - 5C-3

Testing Power Trim Pump
Connecting Test Gauge
1. Check trim pump oil level. Fill if necessary.
2. Place drive unit in the full IN/DOWN position.
3. Connect test gauge at the most convenient loca-
tion (at pump or hydraulic connector).

22090

Gauge Connect to Hydraulic Connector

c - Caps
d - Plugs
26344

Gauge Connected at Pump 4. Open Valve “A” and “B” and run pump UP and
a - Hydraulic Test Gauge 91-52915A6 DOWN several times (to purge air).
b - Extension Hoses 91-52915A6
c - Fittings 22-77366

NOTE: Extension hoses MUST BE used to obtain ac-

curate readings.

22126

a - Hydraulic Test Gauge (91-52915A6)

b - Gimbal Housing Hydraulic Connector

5C-4 – PRESTOLITE POWER TRIM PUMP 90-12934--2 1097

Internal Restriction Test Trim Cylinder Internal Leak
1. Open valve “A” and “B.” Test
2. Run pump OUT/UP and IN/DOWN while observ- IMPORTANT: The following test assumes that
ing gauge. pump OUT/UP pressure is within specifications
3. Replace adapter, if pressure is in excess of 200 as determined by performing “Power Trim Pump
psi (1379 kPa). Test.”
1. Reconnect trim cylinder hoses (if removed in
OUT/UP Pressure Test previous test) as follows:
1. Leave Valve “A” open and close Valve “B.” a. Remove plugs and caps.
2. Run pump OUT/UP while observing gauge. b. Install UP hose to forward hole on hydraulic
Reading should be 2200 - 2600 psi (15173 - connector. Tighten securely.
17932 kPa). If not, replace valve body and gear c. Install DOWN hose to aft hole on hydraulic
assembly. connector. Tighten securely.
3. Stop pumping OUT/UP. Pressure should not fall
below 1900 psi (13104 kPa). If it does, check for
and/or replace following:
• External oil leaks
• Valve Body and Gear Assembly

IN/DOWN Pressure Test

1. Close Valve “A” and open Valve “B.”
2. Run pump IN/DOWN while observing gauge.
Reading should be 400 - 600 psi (2759 - 4138 kPa).
If not, replace valve body and gear assembly.
22090
3. Stop pumping IN/DOWN. Pressure should not
a - UP Hose
fall below 350 psi (2410 kPa). If it does, check for b - DOWN Hose
and/or replace the following: c - Hydraulic Connector
• External oil leaks
• Valve Body and Gear Assembly

90-12934--2 1097 PRESTOLITE POWER TRIM PUMP - 5C-5

2. Connect gauge at most convenient location. 3. Open Valve “A”and “B” and run pump OUT/UP
and IN/DOWN; several times (to purge air).
4. Run pump OUT/UP until trim cylinders are fully
extended; then, observe gauge while pumping.
Pressure should be 2200 - 2600 psi (15173 -
17932 kPa).
5. Stop pumping OUT/UP. Pressure should not fall
below 1900 psi (13104 kPa).
If readings are not within specifications, an in-
ternal trim cylinder leak is indicated. Use the fol-
lowing procedure to locate faulty cylinder.
a. If gauge is connected at pump, reconnect
gauge at gimbal housing hydraulic connec-
tor. Repeat Step 2; then, run pump in OUT/
UP direction until trim cylinder are fully ex-
tended.
b. Close Valve “B” on test gauge and repeat
Steps 3 and 4.
If Readings Are Now Within Specifications: Trim
26345 cylinder on the same side that test gauge is con-
nected, is faulty.
Gauge Connected at Pump
If Readings Are Still Not Within Specifications:
a - Hydraulic Test Gauge 91-52915A3
b - Fitting (22-77366)
Trim cylinder on the opposite side from where the test
c - Fittings (Supplied with Gauge) gauge is connected, is faulty.
d - Black Hydraulic Hose (From Gimbal Housing)
e - Gray Hydraulic Hose (From Gimbal Housing)

22126

Gauge Connected to Hydraulic Connector

a - Test Gauge
b - Coupling (Supplied with Gauge)
c - Front Hydraulic Connector Port

5C-6 – PRESTOLITE POWER TRIM PUMP 90-12934--2 1097

Trim Cylinder Shock Piston Motor and Electrical Bench
Test Tests
If trim system checks out good, but drive unit will not
trim IN/DOWN, problem may be due to a leaky trim Trim Pump Motor Test (In Boat)
cylinder shock piston. Use the following test to check
for this condition. Test gauge is not required. ! WARNING
1. Run pump in OUT/UP direction until trim cylin- DO NOT perform this test near fIammables (or ex-
ders are fully extended. plosives), as a spark may occur when making
2. Prevent trim cylinder piston rods from retracting, connections.
using a suitable device. Quicksilver Trailering Kit
works well for this purpose. ! WARNING
RemaIn clear of drive unit when performing pow-
er trim pump motor tests with pump in the boat
and hydraulic hoses connected.

1. OUT/UP Operation:
a. Connect a jumper wire between positive (+)
solenoid terminal and BLUE/WHITE motor
lead terminal.
b. Motor should run.
22562
a - Trailering Clip

3. Disconnect UP trim hose from trim cylinders.

50523
a - OUT/UP Solenoid
b - POSITIVE Terminal (+)
c - BLUE/WHITE Motor Lead Terminal
d - Jumper Wire
22089
a - UP Trim Hose
b - Front Connection

4. Run pump in IN/DOWN direction. If oil flows from

UP port on trim cylinder, shock piston is leaking
and must be replaced.

90-12934--2 1097 PRESTOLITE POWER TRIM PUMP - 5C-7

2. IN/DOWN Operation: 3. OUT/UP Operation:
a. Connect a jumper wire between positive (+) a. Connect a 12 volt positive (+) supply lead to
solenoid terminal and GREEN/WHITE motor BLUE/WHITE motor lead terminal.
lead terminal.
b. Connect the negative (-) supply lead to a
b. Motor should run. good ground on pump.
c. Motor should run.

50523
a - IN/DOWN Solenoid
b - POSITIVE Terminal (+) 50523
c - GREEN/WHITE Motor Lead Terminal a - OUT/UP Solenoid
d - Jumper Wire b - 12 Volt POSITIVE (+) Supply Lead
c - NEGATIVE (-) Supply Lead
3. If motor does not run, refer to “Motor Repair.” See
Table of Contents.

Trim Pump Motor Test (Out of Boat)

! WARNING
DO NOT perform this test near flammables (or ex-
plosives), as a spark may occur when making
connections.

1. Remove trim pump from boat. Refer to “Trim

Pump Removal.” See Table of Contents.
2. Remove fluid from trim pump reservoir.

5C-8 – PRESTOLITE POWER TRIM PUMP 90-12934--2 1097

4. IN/DOWN Operation: Solenoid Test (Pump in Boat)
a. Connect a 12 volt positive (+) supply lead to
GREEN/WHITE motor lead terminal. ! WARNING
b. Connect the negative (-) supply lead to a DO NOT perform this test near flammables (or ex-
good ground on pump. plosives), as a spark may occur when making
c. Motor should run. connections.

! CAUTION
Remain clear of drive unit when performing pow-
er trim pump motor tests with pump in boat and
hydraulic hose connected.

1. UP/OUT Solenoid:
a. Connect jumper wire between positive (+) so-
lenoid terminal and BLUE/WHITE harness
wire terminal.
b. Motor should run.

50524
a - IN/DOWN Solenoid
b - 12 Volt POSITIVE (+) Supply Lead
c - NEGATIVE (-) Supply Lead

NOTE: If motor does not run, refer to “Motor Repair.”

50521
a - OUT/UP Solenoid
b - Positive (+) Terminal
c - BLUE/WHITE Harness Wire Terminal
d - Jumper Wire

90-12934--2 1097 PRESTOLITE POWER TRIM PUMP - 5C-9

2. IN/DOWN Solenoid: Solenoid Test (Pump Out of Boat)
a. Connect a jumper wire between positive (+)
solenoid terminal and GREEN/WHITE har- ! WARNING
ness wire terminal.
DO NOT perform this test near flammables (or ex-
b. Motor should run. plosives), as a spark may occur when making
connections.

1. Remove trim pump from boat. Refer to “Trim

Pump Removal.” See Table of Contents.
2. Remove fluid from trim pump reservoir.
3. OUT/UP Solenoid:
a. Connect 12 volt positive (+) supply lead to
BLUE/WHITE harness wire terminal.
b. Connect negative (-) supply lead to solenoid
ground terminal.
c. Connect ohmmeter leads to large terminals
on solenoid.

50521
a - IN/DOWN Solenoid
b - Positive (+) Terminal
c - GREEN/WHITE Harness Wire Terminal
d - Jumper Wire

3. If motor does not run in one direction or another,

replace appropriate solenoid. (See Wiring Dia-
gram at end of this section for wire connection
points).

50521
a - OUT/UP Solenoid
b - 12 Volt Positive (+) Supply Lead
c - Negative (-) Supply Lead
d - Ohmmeter Leads

4. Zero Ohms Reading (Full Continuity): Sole-

noid is OK.

High Ohms Reading (No Continuity): Replace

solenoid.

5C-10 – PRESTOLITE POWER TRIM PUMP 90-12934--2 1097

5. IN/DOWN Solenoid: 2. Check for voltage at terminal “2,” using volt me-
ter.
a. Connect 12 volt positive (+) supply lead to
GREEN/WHITE harness wire terminal. Voltage Indicated: Fuse OK.
Voltage Not Indicated: Replace fuse.
b. Connect negative (-) supply lead to solenoid
ground terminal.
c. Connect ohmmeter leads to large terminals
on solenoid.

50523

a - Volt Meter Negative (-) Lead

b - Volt Meter Positive (+) Lead
50521 c - Fuse
a - IN/DOWN Solenoid
b - 12 Volt Positive (+) Supply Lead
c - Negative (-) Supply Lead
d - Ohmmeter Leads

6. Zero Ohms Reading (Full Continuity): Sole-

noid is OK.

High Ohms Reading (No Continuity): Replace

solenoid.
See Wiring Diagram at the end of this section for wir-
ing connection points.

110 Amp Fuse Test (Pump in Boat)

! WARNING
DO NOT perform this test near flammables (or ex-
plosives), as a spark may occur when making
connections.
50524
1. Check for voltage at terminal “1” using a volt me-
a - Volt Meter Negative (-) Lead
ter. Voltage MUST BE indicated before proceed-
b - Volt Meter Positive (+) Lead
ing with next check. c - Fuse

90-12934--2 1097 PRESTOLITE POWER TRIM PUMP - 5C-11

110 Amp Fuse Test (Pump Out of 20 Amp Fuse Test
Boat) 1. Remove fuse from fuse holder.
1. Connect ohmmeter leads between terminals on
fuse.
ZEro Ohms Reading (Full Continuity): Fuse OK
HIGH OHMS READING (No Continuity): Replace
fuse

50521
a - Fuse Holder

2. Connect ohmmeter; one lead to each end of fuse.

50524
Zero Ohms Reading (Full Continuity): Fuse
a - 110 Amp Fuse
OK.
b - Ohmmeter Leads

HIGH OHMS READING (No Continuity):

Replace fuse.

22497
a - 20 Amp Fuse
b - Ohmmeter Leads

5C-12 – PRESTOLITE POWER TRIM PUMP 90-12934--2 1097

Trim Pump Removal Hydraulic Repair
1. Disconnect trim pump battery leads from battery
(negative lead first). Manual Release Valve Replacement
2. Disconnect trim harness connector (3 pronged) NOTE: Replacement of manual release valve can be
from trim pump. completed without removing the trim pump from
boat.
3. Remove hydraulic hoses from trim pump. Cap
end of hoses.
! WARNING
4. Remove lag bolts and washers, and lift pump and
floor bracket from boat. Before loosening the manual release valve, make
sure all people are clear of drive unit as drive unit
will drop to full IN/DOWN position when valve is
loosened.

Slowly turn manual release valve counterclockwise

to remove. To install new valve, turn valve clockwise
until it seats.

50461
a - O-ring
b - Rubber Seal

Disassembly

! CAUTION
50524 Work area must be dirt and lint free. The slightest
a - Positive Battery Lead amount of dirt in hydraulic system can cause
b - Negative Battery Lead pump malfunction.
c - Harness Connector
d - Black Hydraulic Hose (UP Hose) 1. Disconnect trim motor wires.
e - Gray Hydraulic Hose (DOWN Hose)

50520
a - BLUE/WHITE Motor Wire
b - GREEN/WHITE Motor Wire
c - BLACK Ground Wires

90-12934--2 1097 PRESTOLITE POWER TRIM PUMP - 5C-13

2. Remove mounting bolts and remove trim pump Valve Body and Gear Assembly
from floor bracket.
1. Place pump in a container to catch oil when valve
body and gear assembly is removed.

2. Remove valve body, gear assembly and seal.

50522

50460
a - Screws (8)
b - Valve Body And Gear Assembly

50522
a - Trim Pump
b - Floor Bracket
c - Mounting Bolts

3. Remove solenoids (if replacement is necessary).

50520
c - Seal

50520
a - UP Solenoid
b - DOWN Solenoid
c - Mounting Bolts (2 On Each Solenoid)

5C-14 – PRESTOLITE POWER TRIM PUMP 90-12934--2 1097

3. Install new seal in reservoir. 5. Install valve body and gear assembly.

50520
a - Seal

4. Align motor shaft with gear assembly. 50460

a - Screws (8)
b - Valve Body And Gear Assembly
c - New Seal (Not Seen)

Motor Repair
Disassembly
1. Disconnect trim pump motor leads.

50522
a - Motor Shaft
b - Gear Assembly

50459
a - Trim Pump Motor Leads
b - Solenoids

90-12934--2 1097 PRESTOLITE POWER TRIM PUMP - 5C-15

2. Remove solenoid plate and connector and 4. Remove motor assembly.
harness.

50459
a - Solenoid Plate
b - Nut
c - Screws
d - Solenoids
e - Spacer
f - Connector and Harness
26506
3. Remove valve body and gear assembly. a - Nut And Washer (2)
b - End Plate Assembly
c - Field and Frame Assembly
d - Armature
e - Small Thrust Washer(s)
f - Large Thrust Washer
g - Spacer (1)
h - Studs (2)
i - Reservoir

50460
a - Screws (8)
b - Valve Body And Gear Assembly
c - Seal (Not Seen)

5C-16 – PRESTOLITE POWER TRIM PUMP 90-12934--2 1097

Armature Tests 1. Clean commutator with “00” garnet grit sandpa-
per. DO NOT use emery paper.
CONTINUITY TEST 2. Check gaps between commutator bars for mate-
rial. Remove material if present.
1. Check armature for continuity. Set ohmmeter on
Rx1 scale. Connect leads as shown.
Continuity Indicated: Armature is grounded (re-
place armature).
Continuity Not Indicated: Armature is OK.

50520
a - Commutator
b - Gap

50461
Field Test
a - Ohmmeter
b - Meter Lead - Place On Armature Shaft TEST FOR OPEN CIRCUIT
c - Meter Lead - Place On All Commutator Bars (One At A Time)
1. Set ohmmeter to Rx1 scale and connect meter
TEST FOR SHORTS leads between field leads.
Zero Ohms Indicated (Full Continuity): Field OK.
1. Check armature on a growler (follow growler
manufacturers instructions). Indication of a short Zero Ohms Not Indicated (No Continuity):
requires replacement. Replace field assembly.

CLEANING COMMUTATOR

NOTE: If commutator is worn it can be turned down

on a lathe or an armature conditioner tool.

50461
a - Ohmmeter
b - Meter Leads - Connect Between Field Leads
c - Field Leads

90-12934--2 1097 PRESTOLITE POWER TRIM PUMP - 5C-17

TEST FOR SHORT IN FIELD Brush Lead Tests
1. Set ohmmeter on Rx1 scale. Connect ohmmeter
1. Set ohmmeter on Rx1 scale. Connect leads as
between field brush lead and field frame.
shown. Test positive brush lead for ground.
Zero Ohms Indicated (full continuity) - Short
Continuity Indicated: Grounded condition; replace
indicated (Replace field assembly).
end plate assembly.
Zero Ohms Not Indicated (no continuity) - Field OK.
No continuity: Brush lead OK.

50461
a - Ohmmeter
b - Meter Lead - Place On Positive Brush Holder Lead 50460
c - Meter Lead - Place On Frame
a - Ohmmeter
d - Field Lead
b - Meter Lead - Place On Positive Brush Lead
c - Meter Lead - Place On End Cap
Thermal Switch Test
2. Set ohmmeter on rx1 scale. Connect leads as
CONTINUITY TEST shown. Test negative brush lead for an open
condition.
1. Test thermal circuit breaker for continuity, using
ohmmeter set on Rx1 scale. Continuity Indicated: Brush lead OK.

Zero Ohms Indicated (Full Continuity): Thermal Continuity NOT Indicated: Inspect lead for a poor
switch OK. connection.

Zero Ohms Not Indicated (No Continuity):

Replace thermal switch.

26507

a - Place Meter Lead At This Point 50460

b - Place Meter Lead At Ground a - Ohmmeter
b - Meter Lead - Place On Negative Brush Lead
c - Meter Lead - Place On End Cap
d - Positive Brush Lead

5C-18 – PRESTOLITE POWER TRIM PUMP 90-12934--2 1097

Brush Replacement END CAP AND BRUSH ASSEMBLY
REPLACEMENT
Inspect brushes and replace if:
1. Cut off field to positive brush holder lead as close
• Pitted to brush holder as possible.
• Chipped 2. Using 70-30 tin-lead alloy rosin core solder,
solder field lead to brush holder on new end cap.
• Brush is less than 1/4 in. (6mm) long
• Leads are fraying

BRUSH REPLACEMENT
1. Cut brush leads off as close to brush holders as
possible.
2. Using 70-30 tin-lead alloy rosin core solder, sol-
der new brushes to brush holders.

50459

a - Field Lead
b - Positive Brush Holder
c - End Cap

26507
a - Brush Leads
b - Brush Holders

90-12934--2 1097 PRESTOLITE POWER TRIM PUMP - 5C-19

Reassembly NOTE: Brush holder tool can be made as shown.

1. Install armature and washers.

26507

3. Spread brushes with brush holder tool and install

end plate over armature. Secure end cap with
nuts and washers.

26506
a - Large Washer
b - Small Washer(s)
c - Armature
d - Reservoir
e - Long Stud
f - Sleeve (1)
g - Small Stud 26507
h - Connector And Harness Holder

2. Install field and frame assembly. Align index mark

a - End Plate
on field and frame assembly with mark on
reservoir.
4. Ensure seal is in place in reservoir.

50459
50520
a - Index Marks - Align a - Seal
b - Field And Frame Assembly
c - Reservoir

5C-20 – PRESTOLITE POWER TRIM PUMP 90-12934--2 1097

5. Align motor shaft with gear assembly. 7. Install solenoid plate and connector and harness.

50459
a - Solenoid Plate
b - Nut
c - Screws
50522 d - Solenoids
a - Motor Shaft e - Spacer
b - Gear Assembly f - Connector And Harness

6. Install valve body and gear assembly. 8. Secure trim pump motor leads to solenoids.

50460
a - Screws (8)
b - Valve Body and Gear Assembly 50459
c - New Seal (Not Seen) a - Blue Lead - Connect to OUT/UP Solenoid
b - Green Lead - Connect to IN/DOWN Solenoid
c - OUT/UP Solenoid
d - IN/DOWN Solenoid

90-12934--2 1097 PRESTOLITE POWER TRIM PUMP - 5C-21

9. Install trim pump on floor bracket. Tighten Trim Pump Installation
securely.
1. Secure pump and mounting bracket to boat using
lag bolts and washers.
2. Reconnect trim hoses to pump. Black hose to left
connection; gray hose to right connection. DO
NOT cross-thread or overtighten hose fittings.
Torque to 70 - 150 lb. in. (7.9 - 16.9 NSm).
3. Reconnect trim harness connector to trim pump.
4. Reconnect battery leads to battery.
50522
5. Check fluid level and fill if necessary. (Refer to
“Maintaining Power Trim Pump Oil Level” in this
section.)

50522
a - Trim Pump
b - Floor Bracket
c - Screws and Lock Washers

50524
a - Positive Battery Lead
b - Negative Battery Lead
c - Harness Connector
d - Black Hydraulic Hose (UP Hose)
e - Gray Hydraulic Hose (DOWN Hose)

5C-22 – PRESTOLITE POWER TRIM PUMP 90-12934--2 1097

Wiring Diagram

26347

90-12934--2 1097 PRESTOLITE POWER TRIM PUMP - 5C-23

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5C-24 – PRESTOLITE POWER TRIM PUMP 90-12934--2 1097