1988 JEEP CHEROKEE power steering

Wire lead open .......... A .. Require repair or replacement.
Wire lead shorted ....... A .. Require repair or replacement.
(1) - Determine cause and correct prior to repair or
replacement of part.
( 2) - Determine source of contamination, such as engine coolant,
fuel, metal particles, or water. Require repair or
replacement.
( 3) - Inoperative includes intermittent operation or out of
OEM specification. Some components may be serviceable;
check for accepted cleaning procedure.









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SENSORS AND ACTUATORS
NOTE: Conditions pertaining to the sensors and actuators listed
in this section may be found under the name of the sensor
or actuator.
SENSOR ABBREVIATION TABLE









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Sensor Abbreviation
Accelerator Pedal Position Sensor ......................... APP
Air Conditioning Cycling Switch ............................ AC
Air Conditioning Pressure Sensor ........................... ..
Air Fuel Ratio Sensor ...................................... ..
Barometric Pressure Sensor ............................... BARO
Camshaft Position Sensor .................................. CMP
Clutch Pedal Position Switch .............................. CPP
Cooling Fan Motor Sensors and Switches ..................... ..
Crankshaft Position Sensor ................................ CKP
Electronic Transmission Feedback Devices ................... ..
Engine Coolant Temperature Sensor ......................... ECT
Evaporative Emission feedback devices ...................... ..
Exhaust Gas Recirculation feedback devices ................. ..
Fan Control Sensor ......................................... FC
Intake Air Temperature Sensor ............................. IAT
Knock Sensor ............................................... KS
Manifold Absolute Pressure Sensor ......................... MAP
Mass Air Flow Sensor ...................................... MAF
O2 Sensor ................................................. O2S
Park Neutral Position Switch .............................. PNP
Power Steering Pressure Sensor ............................ PSP
Thermal Vacuum Valve ...................................... TVV
Throttle Position Sensor ............................ TP Sensor
Throttle Position Switch ................................... ..
Transmission Range Switch ........................... TR Switch
Vehicle Speed Sensor ...................................... VSS
Volume Air Flow Sensor .................................... VAF









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ACTUATOR ABBREVIATION TABLE








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Actuator Abbreviation
Air Injection Control Solenoid ............................. ..
Electronic Transmission control devices .................... ..
Evaporative Emission Canister ............................ EVAP
Purge Device ............................................... ..
Exhaust Gas Recirculation Device .......................... EGR
Fuel Injector .............................................. ..
Idle Air Control .......................................... IAC

ECU receives inputs from A/C when either A/C switch is in
"ON" position or compressor clutch engages to lower temperature. ECU
changes engine idle speed depending upon A/C compressor operation.
POWER STEERING PRESSURE SWITCH
ECU receives input from pressure switch during periods of
high pump load and low engine RPM. Input signals from pressure switch
to ECU are routed through A/C request and A/C select input circuits.
When pump pressure exceeds 250-300 psi (17.5-21.0 kg/cm
), switch
contacts close transmitting an input signal to ECU. ECU raises engine
idle speed immediately after receiving input from pressure switch.
RELAYS
Starter Motor Relay
Starter motor relay provides an input signal to ECU when
starter motor is engaged.
System Power Relay
System power relay, located on right fender inner panel, is
energized when engine is started. It remains energized for 3 to 5
seconds after ignition is off. This allows ECU to extend ISA for next
start before ECU shuts down.
Fuel Pump Control Relay
Fuel pump control relay is located on right fender inner
panel. Battery voltage is supplied to relay from ignition switch.
When ground is provided by ECU, relay becomes energized and provides
voltage to fuel pump.
A/C Compressor Clutch Relay
ECU controls A/C compressor clutch through this relay. The
A/C compressor clutch relay is located beside fuel pump control relay
on right fender inner panel.
EGR Valve/Canister Purge Solenoid
Vacuum to both EGR valve and vapor canister is controlled by
this solenoid. When solenoid is energized, neither EGR valve nor
vapor canister receive vacuum.
Solenoid is energized during closed (idle) and wide open
throttle operations, engine warm-up and rapid acceleration or
deceleration. If solenoid wire connector is disconnected, both EGR
valve and vapor canister will receive vacuum at all times.
Load Swap Relay
The load swap relay works in conjunction with power steering
switch to disengage A/C compressor clutch. If compressor clutch is
engaged when power steering pressure switch contacts close, input
signal from switch to ECU also activates load swap relay. Relay then
cuts off current to A/C compressor clutch.
The A/C compressor clutch remains disengaged until pressure
switch contacts reopen and engine idle returns to normal. The load
swap relay contains a timer that delays engaging the compressor
clutch for 0.5 second to ensure smooth engagement.
ADJUSTMENTS
CAUTION: When working on or near engine that is running, be very
careful to avoid pulleys, belts and fan. DO NOT stand in
direct line with blades of fan. DO NOT wear clothing that is
loose enough to get caught in moving parts.

Fig. 10: Identification Label Locations
Courtesy of American Motors Corp.
LUBRICATION SPECIFICATIONS
LUBRICATION SPECIFICATIONS TABLE








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Application Fluid Specifications
Automatic Transmission ......................... Dexron-IIE ATF
Brake Master Cylinder ......... DOT 3 (SAE J-1703F) Brake Fluid
Engine Coolant .......... Alugard 340-2 & Water (50/50 Mixture)
Engine Oil ( 1)
Gasoline Engine
Temperature Range
Above 30
\b F (-1\bC) ....... SAE 20W-40 Or 20W-50 API SH/CD
Above 0\b F (-18\bC) ........ SAE 10W-30 Or 10W-40 API SH/CD
Less Than 60\b F (16\bC) .............. SAE 5W-30 API SH/CD
Diesel Engine
Temperature Range
Above 30
\b F (-1\bC) ................ SAE 15W-40, 20W-40 Or
20W-50 API SH/CD
0
\b F (-18\bC) to 100\b F (38\bC) ...... SAE 10W-30 API SH/CD
Less Than 50\b F (10\bC) .............. SAE 5W-30 API SH/CD
Front Axle ................................ SAE 80W-90 API GL-5
Rear Axle ................................. SAE 80W-90 API GL-5
Rear Axle (Trac-Lok) ( 2) ................. SAE 80W-140 API GL-5
Rear Axle (Trailer Towing) ( 3) .......... SAE 75W-140 Synthetic
Hydraulic Clutch .............. DOT 3 (SAE J-1703F) Brake Fluid
Manual Transmission ....................... SAE 75W-90 API GL-5
Manual Steering Box .............. Multi-Purpose NLGI Grade 2EP
Power Steering Pump ...................... Power Steering Fluid
Transfer Case .................................. Dexron-IIE ATF

PO W ER S TE ER IN G G EN ER AL S ER VIC IN G

1988 J e ep C hero ke e
1988 STEERING
Jeep Power Steering General Servicing
Cherokee, Comanche, Grand Wagoneer, Pickup, Wagoneer,
Wrangler
LUBRICATION
SERVICE INTERVALS
Check fluid at every oil change.
CHECKING FLUID LEVEL
Check fluid level with engine stopped and fluid hot or cold.
Fluid level must be at "FULL-HOT" or "FULL-COLD" mark on dipstick. On
models with remote reservoir, keep fluid level 0.5-1.0" from top of
reservoir with wheels turned fully to left.
RECOMMENDED FLUID TABLE









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Application Part Number
Jeep ............................................. 8993342









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REFILLING & BLEEDING SYSTEM
1) Fill reservoir to correct level. Operate engine until
fluid reaches normal operating temperature. Stop engine. Add fluid (if
necessary). Turn wheels to full left position. Add fluid to reservoir
to fill to "FULL-COLD" mark on dipstick.
2) Start and operate engine at fast idle. Recheck reservoir
level. Add to "FULL-COLD" mark on dipstick. Turn wheels from side to
side without contacting stops. Maintain fluid level just above pump
body.
3) When air is removed, return wheels to straight-ahead
position. Operate engine 2-3 minutes. Stop engine. Road test vehicle.
Recheck fluid level. Level should be at "FULL-HOT" position after
system has stabilized. Add fluid (if necessary). DO NOT overfill.
BELT TENSION (Tension in Lbs. Using Boroughs Tension Gauge)









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Application New Belt Used Belt
Jeep ................ ( 1) 125-155 ............... 90-115
( 1) - Cherokee, Comanche and Wagoneer is 120-140 lbs.









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TROUBLE SHOOTING
Refer to TROUBLE SHOOTING - BASIC PROCEDURES article in the
GENERAL TROUBLE SHOOTING section.
TESTING

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 .

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