Gear JEEP CHEROKEE 1988 Service Manual Online
[x] Cancel search | Manufacturer: JEEP, Model Year: 1988, Model line: CHEROKEE, Model: JEEP CHEROKEE 1988Pages: 1378, PDF Size: 19.9 MB
Page 647 of 1378
damaged.
Pump cover wear is measured using a straightedge and feeler
gauge. Pump is to be replaced if warpage or wear exceeds
specifications or mating surface of pump cover is scratched or
grooved.
Fig. 33: Measuring Oil Pump Gear Cavity - Typical
This Graphic For General Information Only
BREAK-IN-PROCEDURE
* PLEASE READ THIS FIRST *
NOTE: Always refer to appropriate engine overhaul article in the
ENGINES section for complete overhaul procedures and
specifications for the vehicle being repaired.
ENGINE PRE-OILING
Engine pre-oiling should be done prior to operation to
prevent engine damage. A lightly oiled pump will cavitate unless oil
pump cavities are filled with engine oil or petroleum jelly.
Page 651 of 1378
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EN G IN E R EM OVA L - 6 -C YL
1988 J e ep C hero ke e
1988 ENGINES
Jeep - Engine Removal - 6-Cylinder
Cherokee, Comanche, Wagoneer, Wrangler
6-CYLINDER ENGINES
4.0L
1) Scribe hinge locations, remove engine compartment light
(if equipped) and remove hood. Disconnect battery cables and remove
battery. Drain cooling system.
2) Disconnect wire connectors from alternator, ignition coil
and distributor. Disconnect oil pressure sender wire, starter wires
and fuel injector wiring harness (if equipped). Detach 2 fuel pipe
quick connect couplings at left inner fender panel. Disconnect engine
ground strap and remove air cleaner.
3) Disconnect the vacuum purge hose at fuel vapor canister
tee. Disconnect wire from idle speed actuator and oxygen sensor.
Detach throttle cable from bracket and disconnect throttle valve rod
at bellcrank. Remove upper and lower radiator hoses.
4) On automatic transmission models, disconnect the
transmission fluid cooler tubing. On all models, remove fan shroud and
radiator. Remove fan and spacer or Tempatrol fan assembly. Hold fan
pulley to water pump flange using 5/16" x 1/2" SAE capscrew while
crankshaft is rotated.
5) Disconnect cruise control cable (if equipped). Disconnect\
wires from starter motor solenoid and disconnect CEC system harness.
Remove power brake vacuum check valve from booster (if equipped).
6) Disconnect power steering hoses from steering gear (if
equipped). Drain power steering pump reservoir and plug end of hoses.
Cap all fittings on steering gear and hoses. Raise and support
vehicle. Remove starter. Remove flywheel housing access cover.
7) Remove upper and loosen lower bellhousing-to-engine bolts.
Attach lifting equipment to engine. Raise engine off front mounts.
Place support under bellhousing. Remove remaining bellhousing-to-
engine bolts. Lift engine out of engine compartment.
4.2L
1) Remove battery and drain cooling system. Remove air
cleaner and engine compartment light from hood. Scribe hinge location
and remove hood. Disconnect and plug front fuel line at pump and fuel
return line at frame.
2) Disconnect heater hoses at heater. Label and disconnect
all wiring, lines, linkage and hoses at engine. Remove vacuum switch
assembly bracket from cylinder head cover. Remove both radiator hoses
and automatic transmission oil lines (if equipped) at radiator. Remove\
radiator and shroud.
3) Remove fan and spacer. Use 5/16" x 1/2" SAE bolt to hold
fan pulley to water pump flange. Remove starter and disconnect engine
ground strap. Remove engine mount-to-bracket nuts. Disconnect exhaust
pipe at manifold.
4) Discharge A/C system (if equipped). Disconnect and plug
hose or port openings at compressor. Disconnect hoses at power
steering gear and drain reservoir. Remove power brake vacuum check
valve. Remove bracket bolt for automatic transmission filler tube (if
equipped).
5) Lift and support vehicle. On models with automatic
Page 688 of 1378
Eroded .................. 1 ............ Suggest replacement.
Loose ................... A .. Require repair or replacement.
Out of specification .... B ............ Require replacement.
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DISTRIBUTOR SHIELDS
See DISTRIBUTOR BOOTS AND SHIELDS .
DISTRIBUTORS
DISTRIBUTOR INSPECTION \
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Condition Code Procedure
Attaching hardware
broken ................. A ... Require repair or replacement
of hardware.
Attaching hardware
missing ................ C .......... Require replacement of
hardware.
Attaching hardware not
functioning ............ A ... Require repair or replacement
of hardware.
Bushings worn, affecting
performance ............ A .. Require repair or replacement.
Bushings worn, not
affecting performance .. 1 .. Suggest repair or replacement.
Cam lobes worn, affecting
performance ............ A .. Require repair or replacement.
Cam lobes worn, not
affecting performance .. 1 .. Suggest repair or replacement.
Gear broken ............. A .. Require repair or replacement.
Gear worn, affecting
performance ............ A ............ Require replacement.
Gear worn, not affecting
performance ............ .. ........ No service suggested or
required.
Integrated pickup
triggering device
loose .................. A .. Require repair or replacement.
Integrated pickup
triggering device
magnetism incorrect .... A .. Require repair or replacement.
Leaking oil internally .. A .. Require repair or replacement.
Noisy ................... 2 .. Suggest repair or replacement.
Pickup triggering device
(reluctor) broken ...... A .. Require repair or replacement.
Pickup triggering device
(reluctor) loose ....... A .. Require repair or replacement.
Pickup triggering device
(reluctor) weak ........ A .. Require repair or replacement.
Reluctor (pickup
triggering device)
broken ................. A .. Require repair or replacement.
Reluctor (pickup
triggering device)
loose .................. A .. Require repair or replacement.
Reluctor (pickup
triggering device)
weak ................... A .. Require repair or replacement.
Shaft bent .............. A ............ Require replacement.
Thrust washer broken .... A .. Require repair or replacement.
Page 774 of 1378
ECU is a digital microprocessor computer. Data sensors
provide the ECU with engine operating information in varying
electrical signals. ECU calculates this information and corrects
air/fuel ratio, ignition timing, and emission control as needed to
maintain efficient engine operation. Other ECU output signals control
upshift indicator light (manual transmission only), ignition module
dwell and A/C clutch operation.
UPSHIFT INDICATOR
On vehicles equipped with a manual transmission, ECU
controls upshift indicator light. Indicator light is normally
illuminated when ignition is turned on without engine running.
Indicator light is turned off when engine is started.
Indicator light will be illuminated during engine operation
in response to engine load and speed. If transmission is not shifted,
ECU will turn light off after 3 to 5 seconds. A switch located on
transmission prevents indicator light from being illuminated when
transmission is shifted to highest gear.
DATA SENSORS & SWITCHES
Manifold Absolute Pressure (MAP) Sensor
MAP sensor is located in engine compartment on firewall,
behind engine. MAP sensor monitors manifold vacuum via a vacuum line
from intake manifold to sensor.
MAP sensor supplies an electrical signal which keeps ECU
informed of manifold vacuum and barometric pressure conditions. This
information is combined with data supplied by other sensors to
determine correct air/fuel ratio.
Oxygen Sensor
Oxygen (O2) sensor is mounted in exhaust manifold where it
is exposed to exhaust gas flow. Its function is to monitor oxygen
content of exhaust gases and to supply ECU with a voltage signal
directly proportional to this content.
If oxygen content of exhaust gases is high (lean air/fuel
mixture), voltage signal to ECU is low. As oxygen content decreases
(mixture becomes richer), signal voltage increases.
In this way, ECU is kept constantly informed of air/fuel
ratio. ECU can then alter fuel injector "on" time, in response to
these signals, to obtain best air/fuel ratio of 14.7:1 under any
given operating conditions.
O2 sensor is equipped with a heating element that keeps
sensor at proper operating temperatures. Maintaining correct sensor
temperatures at all times guarantees a more accurate signal to ECU.
By using an O2 heater, fuel control system may also enter "closed
loop" operating mode sooner and maintain this mode, even during
periods of extended idle.
Temperature Sensors
There are 2 temperature sensors used on this system.
Manifold Air Temperature (MAT) sensor, mounted in intake manifold,
measures temperature of incoming air/fuel mixture and Coolant
Temperature Sensor (CTS), located on left side of cylinder block just
below the exhaust manifold, measures temperature of engine coolant.
Information provided by these 2 sensors to ECU allows ECU to
demand slightly richer air/fuel mixtures and higher idle speeds
during cold engine operation.
Throttle Position Sensor (TPS)
TPS is regulated by movement of throttle shaft. It is
Page 793 of 1378
Coolant temperature sensor is installed in intake manifold
water jacket to provide coolant temperature input signal for ECU.
During cold engine operation, ECU will make mixture richer, make up
for fuel condensation in cold intake manifold, increase idle speed
during warm-up period, increase ignition advance and keep EGR system
inoperative until engine warms up.
THROTTLE POSITION SENSOR (TPS)
Throttle position sensor provides ECU with input signal, up
to about 5 volts, to indicate throttle position. This allows ECU to
control air/fuel mixture according to throttle position. TPS is
mounted on throttle body assembly.
WIDE OPEN THROTTLE (WOT) SWITCH
WOT switch provides an input signal to ECU when engine is at
wide open throttle. The ECU enriches air/fuel mixture. The WOT switch
is located on the side of throttle body.
CLOSED THROTTLE (IDLE) SWITCH
Idle switch is integral with ISA motor and provides voltage
signal to ECU. ECU will signal ISA motor to change throttle stop
angle in response to engine operating conditions.
UPSHIFT INDICATOR LIGHT
On vehicles equipped with a manual transmission, ECU
controls upshift indicator light. Indicator light is normally
illuminated when ignition is turned on without engine running.
Indicator light is turned off when engine is started.
Indicator light will be illuminated during engine operation
in response to engine load and speed. If transmission is not shifted,
ECU will turn light off after 3 to 5 seconds. A switch located on
transmission prevents indicator light from being illuminated when
transmission is shifted to highest gear.
ENGINE SPEED SENSOR
Engine speed sensor is attached to bellhousing. It senses
and counts teeth on flywheel gear ring as they pass during engine
operation. Signal from speed sensor provides ECU with engine speed
and crankshaft angle. On flywheel gear ring, large trigger tooth and
notch is located 90 degrees before each TDC point. Each trigger tooth
is followed by 12 smaller teeth and notches before TDC point is
reached.
As each of 12 small teeth and notches pass magnetic core in
speed sensor, concentration and collapse of magnetic field induces
slight voltage (spike) in sensor pick-up coil winding. See Fig. 2.
Larger trigger teeth and notches induce higher voltage (spike) in
sensor pick-up coil winding. These voltage spikes enable ECU to count
teeth as they pass speed sensor.
Higher voltage spike (from larger tooth and notch) indicates
to ECU that piston will be at TDC position after 12 smaller voltage
spikes have been counted. ECU will then either advance or retard
ignition timing depending upon remaining sensor inputs.
Page 801 of 1378
NOTE: When diagnosing fuel system problems using following
procedures, no specialized service equipment is needed.
Following diagnostic procedures are NOT applicable if
special tester M.S. 1700 is used.
Six different test flow charts are used to fully evaluate
fuel injection system:
TEST 1: IGNITION OFF
This test checks that system power provides for ECU memory
keep-alive voltage.
TEST 2: IGNITION ON: POWER
This test checks system power function and fuel pump power
function.
TEST 3 & 3A: IGNITION ON: INPUT
These tests check the following components and their
circuits: closed throttle (idle) switch, Throttle Position Sensor
(TPS), MAP sensor, A/T gear selector switch, Coolant Temperature
Sensor (CTS) and MAT sensor. Coolant temperature and MAT sensors are
tested in cold condition. This procedure also checks all interrelated
wiring circuits as well.
TEST 4 & TEST 4A: SYSTEM OPERATIONAL
These tests check engine start-up circuit, fuel injector,
"Closed Loop" air/fuel mixture function, coolant temperature sensor
function, MAT sensor function, detonation sensor "Closed Loop"
ignition retard/advance function, EGR valve and canister purge
solenoid function, idle speed control and A/C control functions.
TEST 5: BASIC ENGINE
This test indicates failures in related engine components
that are not part of fuel injection system.
TEST 6: MANUAL TRANSMISSION UPSHIFT
This test checks upshift indicator light function on vehicles
with manual transmissions.
Fig. 5: Jeep/Renix Fuel Injection ECU Connector
Courtesy of Chrysler Motors.
REMOVAL & INSTALLATION
Page 831 of 1378
GEA R T O OTH C O NTA C T P A TTE R NS
1988 J e ep C hero ke e
GENERAL INFORMATION
Gear Tooth Contact Patterns
* PLEASE READ THIS FIRST *
The following article is for GENERAL INFORMATION purposes
only. Information does not SPECIFICALLY apply to all years, makes and
models, but is to be used as a general reference guide.
INSPECTION
PRELIMINARY INSPECTION
Wipe lubricant from internal parts. Rotate gears and inspect
for wear or damage. Mount dial indicator to housing, and check
backlash at several points around ring gear. Backlash must be within
specifications at all points. If no defects are found, check gear
tooth contact pattern.
GEAR TOOTH CONTACT PATTERN
NOTE: Drive pattern should be well centered on ring gear teeth.
Coast pattern should be centered, but may be slightly toward
toe of ring gear teeth.
1) Paint ring gear teeth with marking compound. Wrap cloth or
rope around drive pinion flange to act as brake. Rotate ring gear
until clear tooth contact pattern is obtained.
2) Contact pattern will indicate whether correct pinion
bearing mounting shim has been installed and if drive gear backlash
has been set properly. Backlash between drive gear and pinion must be
maintained within specified limits, until correct tooth pattern is
obtained.
Page 832 of 1378
Fig. 1: Drive Axle Gear Tooth Patterns
ADJUSTMENTS
GEAR BACKLASH & PINION SHIM CHANGES
NOTE: Backlash is adjusted by either moving shims from one side of
differential case to the other or by turning adjusting nuts
on which side bearing races ride. Changing of pinion shims
alters the distance from face of pinion of centerline of
ring gear.
1) With no change in backlash, moving pinion further from
ring gear moves drive pattern toward heel and top of tooth, and moves
coast pattern toward toe and top of tooth.
2) With no change in backlash, moving pinion closer to ring
gear moves drive pattern toward toe and bottom of tooth, and moves
coast pattern toward heel and bottom of tooth.
3) With no change in pinion shim thickness, an increase in
backlash moves ring gear further from pinion. Drive pattern moves
toward heel and top of tooth, and coast pattern moves toward heel and
top of tooth.
4) With no change in pinion shim thickness, decrease in
Page 833 of 1378
backlash moves ring gear closer to pinion gear. Drive pattern moves
toward toe and bottom of tooth, and coast pattern moves toward toe and
bottom of tooth.
Page 845 of 1378
IG NIT IO N S W IT C H & L O CK C YLIN DER
1988 J e ep C hero ke e
1988 Ignition Switch & Lock Cylinders
JEEP
DESCRIPTION
The ignition switch and lock cylinder is typically mounted on
the steering column and actuated by an ignition key.
SERVICING
To gain access to ignition components on Jeep vehicles, the
steering column must be removed or lowered and the turn signal switch
must be removed.
CAUTION: The lock plate is held by high spring pressure. DO NOT
remove snap ring without using a compressor tool. If the
steering shaft has standard threads, use Compressor Tool
(J-23653); if the shaft has metric threads use Metric
Forcing Screw (J-23653-4).
CAUTION: Special care must be taken to avoid bumping, jolting or
hammering on the steering shaft and gearshift tube.
REMOVAL & INSTALLATION
LOCK CYLINDER
Removal
Turn lock cylinder clockwise 2 detent positions beyond
"OFF-LOCK" position. Compress lock cylinder retaining tab using a thin
bladed screwdriver and remove lock cylinder.
Fig. 1: Typical Column Type Ignition Switch Lock Cylinder Removal
On most vehicles, push in to release lock retainer.
Installation
Insert key in lock. Hold cylinder sleeve, and turn key