1988 JEEP CHEROKEE wheel
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Crankshaft End Play
1) Using dial indicator, check crankshaft end play. Inspect
crankshaft thrust surfaces or thrust bearing for wear if not within
specification. See ENGINE SPECIFICATIONS table.
2) Replace thrust bearing if required. When replacing thrust
bearing, pry crankshaft forward then reward prior to tightening main
bearing cap to specification. Recheck end play. Replace crankshaft if
not within specification.
REAR MAIN BEARING OIL SEAL
Removal
Remove transmission, clutch housing and flywheel or drive
plate. Using screwdriver, pry oil seal from housing. Avoid damage to
surrounding area.
NOTE: Shim must be used when installing old type oil seal Part No.
(324 1669) only. DO NOT use shim when installing new type
oil seal Part. No. (8933 004 143).
Installation
1) Position wing nut on Seal Installer (J-36306) until it
contacts the shaft nut. See Fig. 7. Install shim if old type seal Part
No. (324 1669) is used.
2) Lubricate inner and outer edges of seal. Install seal on
seal installer with seal dust shield toward the wing nut. Install seal
installer on crankshaft so pilot and dowel are positioned on the
crankshaft.
3) Thread the seal installer attaching screws into the
crankshaft and tighten. Rotate wing nut until it bottoms. This will
properly position the seal.
4) Remove seal installer. Ensure dust shield is not curled
under. Reverse removal procedures for remaining components.
Fig. 7: Installing Rear Main Bearing Oil Seal
WATER PUMP
Removal
Page 14 of 1378
![JEEP CHEROKEE 1988 Service Repair Manual Fig. 9: Measuring Oil Pump Gear End Clearance
TORQUE SPECIFICATIONS
TORQUE SPECIFICATIONS TABLE \
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TORQUE SPECIFICATIONS
TORQUE SPECIFICATIONS TABLE \
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Fig. 9: Measuring Oil Pump Gear End Clearance
TORQUE SPECIFICATIONS
TORQUE SPECIFICATIONS TABLE \
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Application Ft. Lbs. (N.m)
Camshaft Sprocket Bolt .......................... 80 (109)
Connecting Rod Cap Nut ........................... 33 (45)
Cylinder Head Bolt
No. 8 ........................................ 100 (136)
All Others ................................... 110 (149)
Drive Plate-to-Converter Bolt .................... 22 (30)
EGR Valve Pipe Nut ............................... 30 (41)
Exhaust Manifold Bolt ............................ 23 (31)
Fan Bolt ......................................... 18 (24)
Flywheel-to-Crankshaft Bolt .................. ( 1) 50 (68)
Intake Manifold Bolt ............................. 23 (31)
Main Bearing Cap Bolt
Page 20 of 1378
with manifold pressure information.
Knock Sensor
The knock (detonation) sensor, located in the cylinder head,
provides an input signal to the ECU whenever detonation occurs. The
ECU then retards ignition advance to eliminate the detonation at the
applicable cylinders.
Speed Sensor
The speed sensor (or crankshaft position sensor) is mounted
at the flywheel/drive plate housing. The sensor detects the flywheel/
drive plate teeth as they pass during engine operation and sends an
electrical signal to the ECU, which calculates engine speed.
The flywheel/drive plate has a large trigger tooth and notch
located 90
and 12 small teeth before each top dead center (TDC)
position. When a small tooth or notch pass the magnetic core in the
sensor, the build-up and collapse of the magnetic field induces a
small voltage signal in the sensor pick-up windings.
The ECU counts these signals representing the number of teeth
as they pass the sensor. When a larger trigger tooth and notch pass
the magnetic core, a higher voltage signal is sent to the ECU. This
indicates to the ECU that a piston will be at the TDC position 12
teeth later. The ECU either advances or retards ignition timing as
necessary according to sensor inputs.
Battery Voltage
Battery voltage input to the ECU ensures that proper voltage
is applied to the injector. The ECU varies voltage to compensate for
battery voltage fluctuations.
Starter Motor Relay
The engine starter motor relay provides an input to the ECU,
indicating the starter motor is engaged.
Wide Open Throttle (WOT) Switch
The WOT switch is mounted on the side of the throttle body.
The switch provides a voltage signal to the ECU under wide open
throttle conditions. The ECU responds to this signal by enriching the
air/fuel mixture delivered to the injector.
Closed Throttle (Idle) Switch
This switch is integral with the idle speed actuator (ISA)
motor. The switch provides a voltage signal to the ECU, which
increases or decreases the throttle stop angle in response to engine
operating conditions.
Transmission Gear Position Indicator
The gear position indicator is mounted on vehicles equipped
with automatic transaxles. It provides a signal to the ECU to
indicate that the transaxle is in a driving mode and not in Park or
Neutral.
Power Steering Pressure Switch
The switch increases the idle speed during periods of high
power steering pump load and low engine RPM.
A/C Switch
The A/C switch sends a signal to the ECU when the air
conditioner is operating and when the compressor clutch must be
engaged to lower the temperature. The ECU, in turn, increases engine
speed to compensate for the added load of the air conditioner.
FUEL CONTROL
Page 28 of 1378
NOTE: Voltage should drop 0.5-1.5 volts with hot engine, at idle.
Fig. 6: MAP Sensor Terminal Identification
If markings on MAP sensor vary from illustration, use markings on
sensor.
2) Test voltage at pin 33 of ECU connector for 4.0-5.0 volts
to verify wiring harness condition. Repair if required.
3) With ignition on, check for MAP sensor supply voltage of
4.5-5.5 volts at sensor connector pin C. Similar voltage should be
present at pin 16 of ECU connector. Repair or replace wiring harness
if required. Test for sensor ground between pin 17 of ECU connector
and pin A of sensor connector.
4) Using an ohmmeter, check for ground from pin 17 of ECU
connector to pin 2. If an open circuit is indicated, check for a
defective sensor ground on the flywheel housing near the starter
motor.
5) If ground is good, the ECU must be replaced. Before
replacing ECU, check to see if pin 17 of ECU connector is shorted to
12 volts. If so, correct the condition and test ECU before replacing.
Refer to the ELECTRONIC CONTROL UNIT TEST.
ELECTRONIC CONTROL UNIT
Page 69 of 1378
![JEEP CHEROKEE 1988 Service Repair Manual TORQUE SPECIFICATIONS TABLE \
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TORQUE SPECIFICATIONS TABLE \
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Application Ft. Lbs. (N.m)
Camshaft Sprocket Bolt .......................... 80 (109)
Connecting Rod Cap Nut ........................... 33 (45)
Crankshaft Pulley-to-Damper Bolt ................. 20 (27)
Cylinder Head Bolt
4.0L
No. 11 .................................... 100 (135)
All Others ................................. 110 (149)
4.2L
No. 11 ..................................... 75 (102)
All Others .................................. 85 (115)
Exhaust Pipe-to-Manifold Bolt .................... 20 (27)
Fan & Hub Bolt ................................... 18 (24)
Flywheel-to-Crankshaft Bolt .................... 105 (142)
Fuel Rail Bolt ................................... 20 (27)
Intake & Exhaust Manifold Bolt
4.0L
Exhaust Manifold Bolts 1-5 ................... 23 (31)
Exhaust Manifold Bolts 6-7 .................. 17 (23)
Exhaust Manifold Bolts 8-11 ................. 23 (31)
Exhaust Manifold Bolts 12-13 ................ 30 (41)
4.2L ........................................... 23 (31)
Main Bearing Cap Bolt
Step 1 ......................................... 40 (54)
Step 2 ......................................... 70 (95)
Step 3 ........................................ 80 (109)
Oil Pump Attaching Bolt
Short .......................................... 10 (14)
Long ........................................... 17 (23)
Oxygen Sensor .................................... 35 (47)
Rocker Arm Bolt .................................. 19 (26)
Vibration Damper Bolt ....................... (1) 80 (109)
Water Pump Bolts ................................. 13 (18)
INCH Lbs. (N.m)
Engine Front Cover
Bolt ............................................ 60 (7)
Studs ......................................... 192 (22)
Oil Pan Bolt
1/4" X 20 ....................................... 84 (9)
5/16" X 18 .................................... 132 (15)
Oil Pump Cover Bolt ............................... 70 (8)
Valve Cover Bolt .................................. 55 (5)
( 1) - Clean and lubricate with oil prior to tightening.
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ENGINE SPECIFICATIONS
GENERAL ENGINE SPECIFICATIONS
GENERAL SPECIFICATIONS TABLE \
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Application In. (mm)
4.0L
Displacement
Page 75 of 1378
ECU signal line and the other end connected to ground. As throttle
valve angle changes, a return voltage is sent back to the ECU through
the third wire. Output voltage to the ECU is about one volt when
throttle valve is at idle position, and about 5 volts when throttle
valve is at wide open throttle.
A dual TPS is used on automatic transmission equipped models.
The additional sensor provides throttle position information to the
transmission.
Knock Sensor
A knock sensor is mounted on the lower left side of block,
just above the oil pan. This sensor detects abnormal engine vibration
due to "detonation" and/or "pre-ignition". The knock sensor supplies
detonation information to the ECU. The ECU then alters ignition timing
as needed to maintain maximum timing under most operating conditions.
Park/Neutral (P/N) Switch
The P/N switch is mounted in automatic transmission equipped
vehicles. The switch indicates when the transmission is in Park or
Neutral.
Speed Sensor
The speed sensor is a nonadjustable sensor attached to the
flywheel/drive plate housing with special shoulder bolts. This sensor
provides Top Dead Center (TDC) and engine speed information to the ECU\
by counting the flywheel teeth as they pass during engine operation.
The flywheel has a large trigger tooth and notch located 12 small
teeth before each TDC position. See Fig. 2.
Fig. 2: Design of Speed Sensor
When a small tooth and notch pass the magnetic core of the
sensor, the concentration and collapse of the magnetic field created
induces a small voltage spike into the sensor pick-up coil windings.
Page 93 of 1378
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EAC Electric Assist Choke")
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EAC Electric Assist Choke
EACV Electric Air Control Valve
EBCM Electronic Brake Control Module
ECA Electronic Control Assembly
ECAT Electronically Controlled Automatic Transaxle
ECM Electronic Control Module
ECT Engine Coolant Temperature Sensor
ECU Electronic Control Unit or Engine Control Unit
EDF Electric Drive Fan relay assembly
EDIS Electronic Distributorless Ignition System
EEC Electronic Engine Control
EECS Evaporative Emission Control System
EEPROM Electronically Erasable PROM
EFE Early Fuel Evaporation
EFI Electronic Fuel Injection
EGO Exhaust Gas Oxygen sensor (see HEGO)
EGR Exhaust Gas Recirculation system
EGRC EGR Control solenoid or system
EGRV EGR Vent solenoid or system
EMR Emission Maintenance Reminder Module
ESA Electronic Spark Advance
ESC Electronic Spark Control
EST Electronic Spark Timing
ETR Emergency Tensioning Retractor
EVAP Fuel Evaporative System
EVIC Electronic Vehicle Information Center
EVO Electronic Variable Orifice
EVP EGR Valve Position Sensor
EVR EGR Valve Regulator
EVRV Electronic Vacuum Regulator Valve
Elect. Electronic
Eng. Engine
Evap. Evaporative
Exc. Except
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"F" ABBREVIATION TABLE
"F" ABBREVIATION TABLE \
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ABBREVIATION DEFINITION
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F Fahrenheit (Degrees)
F/B Fuse Block
FBC Feedback Carburetor
FI Fuel Injector or Fuel Injection
FICD Fast Idle Control Device
FIPL Fuel Injector Pump Lever
FP Fuel Pump
FPM Fuel Pump Monitor
FPR-VSV Fuel Pressure Regulator Vacuum Switching Valve
FWD Front Wheel Drive
Fed. Federal
Ft. Lbs. Foot Pounds
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"G" ABBREVIATION TABLE
"G" ABBREVIATION TABLE \
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ABBREVIATION DEFINITION
Page 98 of 1378
RVB Rear Vacuum Break
RWAL Rear Wheel Anti-Lock Brake
RWD Rear Wheel Drive
Recirc. Recirculate or Recirculation
Reg. Regulator
Rly. Relay
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"S" ABBREVIATION TABLE
"S" ABBREVIATION TABLE \
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ABBREVIATION DEFINITION
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SAW Spark Angle Word
SBC Single Bed Converter
SBEC Single Board Engine Controller
SC Super Charged
SCC Spark Control Computer
SCS Air Suction Control Solenoid
SDM Supplemental Restraint System Diagnostic Module
SDU SRS Diagnostic Unit
SEN Sensor
SES Service Engine Soon
SFI Sequential (Port) Fuel Injection
SIG RTN Signal Return circuit
SIL Shift Indicator Light
SIR Supplemental Inflatable Restraint
SMEC Single Module Engine Controller
SOHC Single Overhead Cam
SOL or Sol. Solenoid
SPFI Sequential Port Fuel Injection
SPK Spark Control
SPOUT Spark Output Signal
SRS Supplemental Restraint System (Air Bag)
SS 3/4-4/3 Shift Solenoid circuit
SSI Solid State Ignition
STAR Self-Test Automatic Readout
STI Self Test Input circuit
STO Self-Test Output
SUB-O2 Sub Oxygen Sensor
Sen. or Sens. Sensor
Sol. Solenoid
Sprchg. Supercharger
Strg. Steering
Susp. Suspension
Sw. Switch
Sys. System
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"T" ABBREVIATION TABLE
"T" ABBREVIATION TABLE \
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ABBREVIATION DEFINITION
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T.V. Throttle Valve
TAB Thermactor Air By-Pass
TAC Thermostatic Air Cleaner
TAD Thermactor Air Diverter
TAN Tan
TBI Throttle Body Injection