1988 JEEP CHEROKEE Service Repair Manual

PREPARATION
1) With belt tension correct, disconnect power steering pump
pressure hose. Keep hose end raised to prevent fluid loss. Connect
pressure hose of gauge to power steering pump fitting. Connect other
hose from valve side of tester to steering gear inlet.
2) Open valve. Run engine until fluid reaches normal
operating temperature of 170
F (77C). Check fluid level. Add fluid
(if necessary).
PRESSURE TEST
1) Note pressure reading with valve open and engine idling.
Pressure should be 80-125 psi (5.6-8.8 kg/cm).
2) If pressure is above 200 psi (14.1 kg/cm), check hoses
for restrictions and poppet valve (Saginaw gears) for proper assembly.\
3) Close gate valve completely and reopen 3 times. Record
highest reading each time. DO NOT close valve for more than 5 seconds.
If pressure is less than specification, clean or replace flow control
valve in pump. If pressures are still low, replace pump.
4) If readings are within specifications and within 50 psi
(3.5 kg/cm
) of each other, pump is operating properly. Refer to the
PRESSURE TEST SPECIFICATIONS table. If pressures are high, but do not
repeat within 50 psi (3.5 kg/cm
), flow control valve in pump is
sticking. Remove flow control valve. Clean or replace flow control
valve.
5) If pump is within specifications, open valve and turn
steering wheel from right to left stops. Record pressure. DO NOT hold
wheel against stops more than 5 seconds.
6) Pressure should measure the same as specified. See the
PRESSURE TEST SPECIFICATIONS table. If pressure is low, steering gear
is leaking internally and must be overhauled.
7) Turn steering wheel from left to right with engine idling
at 600-800 RPM. See PRESSURE TEST SPECIFICATIONS table.
8) If pressure is low, momentarily close valve. If pressure
is less than specified, pump is faulty. If pressure is within
specification but was low at previous reading, steering gear is
faulty.
PRESSURE TEST SPECIFICATIONS TABLE









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Application Idle: psi (kg/cm) Relief: psi (kg/cm)
Jeep ............... 80-125 (6-9) ............. 1400-1500 (98-105\
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PO W ER S TE ER IN G P U M P

1988 J e ep C hero ke e
1988 STEERING
Jeep Power Steering Pumps - Saginaw Vane-Type
Cherokee, Comanche, Grand Wagoneer, Pickup, Wagoneer,
Wrangler
DESCRIPTION
Saginaw vane-type power steering pump can be identified by
"ham-shaped" fluid reservoir can. Rectangular pumping vanes carried by
a shaft driven rotor move fluid from intake to pressure cavities of
cam ring.
Centrifugal force throws vanes against inside surface of cam
ring to pick up residual oil. As more oil is picked up, it is forced
into cavities of thrust plate, into 2 cross-over holes in cam ring and
pressure plate and into a high pressure area between pressure plate
and housing end plate.
Filling the high pressure area causes oil to flow under vanes
in slots of rotor. This forces vanes to follow inside oval surface of
cam ring. As vanes rotate to small area of cam ring, oil is forced out
from between vanes.
TROUBLE SHOOTING
Refer to TROUBLE SHOOTING - BASIC PROCEDURES article in the
GENERAL TROUBLE SHOOTING section.
LUBRICATION & TESTING
See POWER STEERING GENERAL SERVICING article in the STEERING
section.
REMOVAL & INSTALLATION
POWER STEERING PUMP
Removal & Installation
1) Loosen pump adjusting bolt (or nut) and pump mounting
bolts. Remove pump drive belt. Disconnect pressure and return hoses
from pump. Cap ends to prevent loss of fluid or contamination.
2) Remove pump bracket-to-engine bolts. Remove pump, pulley
and mounting bracket as an assembly. To install, reverse removal
procedure. Bleed system.
OVERHAUL
CAUTION: When clamping pump in vise, be careful not to exert
excessive force on front hub or pump. DO NOT use hammer to
remove pulley.
DISASSEMBLY
1) Drain pump reservoir. Clean exterior of unit. Remove
mounting bracket(s). Using a puller, withdraw pulley from shaft. See
Fig. 1 .

Fig. 1: Removing Pump Pulley
2) Clamp pump, with shaft pointing down and at the square
boss of the shaft housing, into a soft-jawed vise. Remove pressure
line union and "O" ring. Remove reservoir retaining studs.
3) Tap against filler tube with plastic hammer to loosen
reservoir on pump body. Remove reservoir from body. Remove and discard
"O" rings.
4) Using 1/8" punch, tap end plate retaining ring around
until end of ring is near hole in pump body. Inserting punch in hole,
disengage ring from groove in pump bore. Using a screwdriver, pry ring
from body. See Fig. 2.
Fig. 2: Removing Pump End Plate Retaining Ring
5) Tap end plate with a soft-faced hammer to loosen. Spring
tension should push plate up. Remove spring. Remove pump from vise.
6) Invert pump and place on flat surface. Using soft-faced

hammer, tap end of drive shaft to loosen pressure plate, rotor, and
thrust plate assembly from body.
7) Lift pump body off rotor assembly. Flow control valve and
spring should slide out of bore. Remove and discard end plate and
pressure plate "O" rings.
8) Using a screwdriver, pry drive shaft oil seal from body.
Lift pressure plate and cam ring from rotor. Remove rotor vanes.
9) Clamp drive shaft in soft-jawed vise, with rotor and
thrust plate facing up. Remove rotor lock ring from shaft. Use care
not to nick shaft or rotor. Slide rotor and thrust plate off shaft.
Remove shaft from vise.
CLEANING & INSPECTION
1) Clean all pump components (except drive shaft seal) in
clean solvent. Blow dry. Inspect flow control valve assembly for wear,
scoring, burrs or other damage. Inspect seal bore for burrs, nicks, or
score marks that would allow oil to by-pass outer seal surface.
2) Check all machined surfaces of body for scratches or burrs
which might allow leaks. Check "O" ring mating surfaces. Inspect pump
body drive shaft bushing for excessive wear.
3) If replacement is required, replace pump body and bushing
as an assembly. Inspect end cover "O" ring mating surface for nicks
and burrs. Polish with oil stone (if necessary).
4) Inspect rotor ring for roughness or irregularities. Use
oil stone to correct minor irregularities. Replace ring if outside cam
surface is worn or scored. Check thrust plate and pressure plate for
scoring and wear.
5) To remove light scoring, lap with crocus cloth until
surface is smooth and flat. Clean thoroughly. Check that vanes slide
freely but fit snugly into slots.
6) If vanes are loose in slots, replace rotor and/or vanes.
Scoring on rotor may be removed by lapping with crocus cloth. Clean
thoroughly.
REASSEMBLY
1) Lubricate all "O" rings, seals and seal surfaces with
power steering fluid. On Jeeps, lubricate "O" rings with petroleum
jelly. With pump on flat surface, drive new shaft seal in until it
bottoms on bore shoulder.
2) Clamp body in vise with shaft pointing down. Install end
plate and pressure plate "O" rings on body. Install body to reservoir
"O" rings. Install on pump body.
3) Place shaft, splined end up, in soft-jawed vise. Install
thrust plate on shaft with smooth, ported side up. Slide rotor,
counter bore down, over splines.
4) Install new rotor lock ring. Ensure ring is seated in
groove. Install 2 dowel pins into holes in pump cavity. Insert drive
shaft, rotor, and thrust plate assembly into pump cavity. Align
locating holes with dowel pins.
5) Slide cam ring over rotor and onto dowel pins, with arrow
on ring facing toward rear of housing. Install vanes in rotor slots
with radius edge facing out towards cam ring inner surface. Position
pressure plate on dowel pins with circular spring depression facing
rear of housing.
6) Using a 1 1/4" socket in groove of pressure plate, press
down on socket with both thumbs to seat assembly on "O" ring in pump
cavity. Place spring in groove in pressure plate. Place end cover lip
edge over spring.
7) Using thumb or arbor press, press end cover down below
retaining ring groove. Seat retaining ring in groove. Take care to
prevent cocking end cover in bore or distorting assembly.

8) Using a punch, tap retaining ring ends around in groove
until opening is opposite flow control valve bore. This ensures
maximum retention of retaining ring.
9) Install new "O" rings to reservoir, mounting studs, and
flow control valve. Place reservoir on pump body. Align mounting stud
holes. Install studs.
10) Using a soft-faced hammer, tap reservoir down on pump.
Install flow control valve spring and valve assembly slotted end up.
Install new "O" ring on pressure hose fitting uppermost groove.
CAUTION: DO NOT install pressure hose "O" ring in lower groove. This
will restrict relief outlet orifice.
11) Install pressure hose fitting. Tighten mounting studs.
Tighten hose fitting. Remove pump from vise. Install mounting bracket
and pulley.
Fig. 3: Exploded View of Power Steering Pump
Fig. 4: Exploded View of Control Valve Assembly

Fig. 5: Installing Pump Pulley
TORQUE SPECIFICATIONS
TORQUE SPECIFICATIONS TABLE








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Application Ft. Lbs. (N.m)
Gear End Hose Fittings ............................ 20 (27)
Pump End Hose Fittings ............................ 20 (27)
Bracket Bolts ..................................... 35 (48)









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PO W ER W IN DO W S

1988 J e ep C hero ke e
1988 Power Windows
JEEP SIDE & TAILGATE WINDOWS
Cherokee, Comanche, Grand
Wagoneer, Wagoneer
DESCRIPTION
All models have a tape-driven window regulator system in the
side doors, and a mechanical regulator in rear door of Grand Wagoneer.
On Grand Wagoneer, the tailgate window operates on 2 circuits, from an
instrument panel switch or an external key switch at the tailgate.
Side windows are operated by individual switches at each door, or by a
complete set of control switches at the instrument panel or drivers
door. The system is protected by a 30 amp circuit breaker in the fuse
panel.
TESTING
NOTE: Ensure instrument panel tailgate switch is properly grounded
as motor grounds through switch. The electric tailgate and
defogger switch are serviced as an assembly.
INSTRUMENT PANEL TAILGATE SWITCH
Grand Wagoneer
1) Turn ignition on. Using a 12-volt test light, connect one
end of test light to ground and probe Red wire. If test light does not
glow, repair feed circuit.
2) If test light glows, probe Brown wire with switch in "UP"
position. If test light does not glow, replace switch. If test light
glows, move switch to "DOWN" position and probe Tan wire. If test
light does not glow, replace switch. If test light glows, check
tailgate window switch.
TAILGATE WINDOW SWITCH
Grand Wagoneer
1) Using a 12-volt test light, connect one end of test light
to ground and probe Red wire of tailgate window switch. If test light
does not glow, repair feed circuit.
2) If test light glows, probe Tan wire. Turn tailgate switch
to "DOWN" position. If test light does not glow, replace switch. If
test light glows, probe Brown wire. Turn tailgate switch to "UP"
position.
3) If test light does not glow, replace switch. If test light
glows, check tailgate window safety switch.
TAILGATE WINDOW SAFETY SWITCH
Grand Wagoneer
1) Using a 12-volt test light, connect one end of test light
to ground and probe Brown wire of safety switch. Turn tailgate switch
to "UP" position. If test light glows, voltage is present at switch.
If test light does not glow, check feed circuit and repair as
necessary.
2) Probe Brown wire. Turn tailgate switch to "UP" position
and close safety switch. If test light does not glow, replace switch.

If test light glows, check tailgate window motor.
TAILGATE WINDOW MOTOR
Grand Wagoneer
1) Using a 12-volt test light, connect one end of test light
to ground and probe Tan wire at motor. Close safety switch and turn
tailgate window switch to "DOWN" position. If test light glows and
motor does not operate, replace motor. If test light does not glow,
check feed circuit to motor and repair as necessary.
2) Probe Brown wire at motor. Close safety switch and turn
tailgate window switch to "UP" position. If test light glows and motor
does not operate, replace motor. If test light does not glow, check
feed circuit to motor and repair as necessary.
SIDE WINDOW MASTER SWITCH CIRCUIT
1) Remove escutcheon and housing from master switch. Separate
terminal plate by releasing retainer hooks to expose terminal ends.
Turn ignition on.
2) Using a 12-volt test light, connect one lead to Black wire
and other lead to Red terminal. Repeat test at second Black wire. If
test light does not glow in either test, remove lead to Black terminal
and connect to chassis ground.
3) If test light glows, an open exists between master switch
and ground. If test light does not glow, it indicates a defective
circuit breaker or an opening in the Red wire from circuit breaker to
master switch.
SIDE WINDOW CONTROL SWITCH & MOTOR TEST
Grand Wagoneer
1) Connect test light between terminals of Orange and Yellow
wires. Operate control switch up and down. If test light glows in both
switch positions, wires, individual door and master switches are not
defective.
2) Disconnect White and Green motor leads at terminal plate,
and connect to Green and White leads. Operate master switch. If window
goes up and down, motor is okay, but switch is defective. If motor
does not operate, remove trim panel and check connections and leads to
motor. If motor operates, switch is defective.
SIDE WINDOW MOTOR
Connect test battery positive lead to one of the motor
terminals. Connect negative lead to other terminal. Motor should
rotate in one direction to go up or down. Reverse battery leads, motor
should rotate in opposite direction. If window does not move, replace
motor.
SWITCH VOLTAGE TEST
1) Turn ignition on. Remove switch from trim panel.
Disconnect terminal block on wiring harness from switch body. Connect
one lead of test light to Red wire terminal and other end to ground.
2) If test light glows, wiring between battery and switch is
functional. Check continuity in Black wire (ground). If test light
does not glow, check circuit breaker. If okay, check for a broken
wire.
SWITCH UP & SWITCH DOWN TEST