1988 JEEP CHEROKEE turn signal

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

SPARK PLUG CHECK
Faulty or fouled plugs may perform well at idle speed, but at
higher engine speeds, they frequently fail. Faulty plug can exhibit
the following symptoms:
* Poor fuel economy.
* Power loss.
* Decreased engine speed.
* Hard starting.
* Generally poor performance.
Spark plugs also malfunction due to carbon fouling,
excessive electrode air gap, or broken insulators.
SYNC PULSE SIGNAL GENERATOR (STATOR) TEST
NOTE: For this test, an analog voltmeter MUST be used.
1) Insert the positive (+) lead of the voltmeter into the
Blue wire at the distributor connector.
2) Insert the negative (-) voltmeter lead into the Gray/Whit\
e
wire at the distributor connector.
CAUTION: DO NOT remove the distributor connector from distributor.
Insert the voltmeter leads into the backside of the
distributor connector to make contact with the terminals.
3) Set the voltmeter to the 15-Volt D/C scale. Turn ignition
key to "ON".
4) The voltmeter should display approximately 5.0 volts.
5) If no voltage displays, check that the voltmeter leads are
making good contact. If there is still no voltage, go to next step.
6) Remove the ECU and check for voltage at pin "C-16" and
ground with harness connected. If there in still no voltage, proceed
to the next step.
7) Connect Diagnostic Tester M.S. 1700 to the vehicle. Using
the diagnostic tester, perform vehicle test. If voltage is present, go
to the next step.
8) Check for continuity between the Blue wire at the
distributor connector and pin C-16 at the ECU.
9) If there in no continuity, repair harness as necessary.
10) Check for continuity between the Gray/White wire at the
distributor connector and pin C-5 at the ECU.
11) If there is no continuity, repair harness as necessary.
12) Check for continuity between the Black wire at the
distributor connector and ground.
13) If there is no continuity, repair harness as necessary.
14) While observing the voltmeter, crank the engine; the
voltmeter needle should fluctuate back and forth while the engine in
cranking. A fluctuation verifies that the stator in the distributor is
operating properly.
15) If there is no pulse sync, replace the stator. Refer to
REMOVAL & INSTALLATION below in this article.
REMOVAL & INSTALLATION
COOLANT TEMPERATURE SENSOR (CTS)
Removal
1) Drain the cooling system.

Electronic Spark Timing (EST) is used on most computer
controlled systems. The Electronic Control Module (ECM) monitors
information from various engine sensors, computes desired spark
timing, and signals distributor for correct timing change. The HEI
distributor with EST does not have centrifugal advance weights,
springs, or a vacuum advance unit. See Figs. 2 and 3.
HEI & EST WITH ELECTRONIC SPARK CONTROL (ESC)
All fuel injected vehicles are equipped with Electronic Spark
Control (ESC). ESC systems contain a knock sensor mounted in the
engine block. A Blue wire connects the sensor to the ESC module. If
the sensor detects knock, it sends a signal to the module which, in
turn, signals the ECM. The ECM sends a signal to the distributor to
retard spark timing.
Fig. 2: Typical HEI/EST Distributor, Integral coil system shown.
Courtesy of General Motors Corp.
OPERATION

The ECM monitors information concerning crankshaft position,
engine RPM, engine load, atmospheric conditions, engine temperature,
and transmission gear position. This information is used by the ECM to
compute desired spark timing which is relayed to the distributor,
enabling appropriate changes to be made to ignition timing. A back-up
spark advance system is incorporated to signal ignition module in the
event of ECM failure.
CAUTION: Although similar in appearance, components of HEI/EST and
HEI distributors are NOT interchangeable.
All Models With EST
The distributor module is connected to ECM by a 4-wire EST
connector which performs the following functions:
* Terminal "A" of the 4-wire connector is the reference ground
low. It is grounded in the distributor and ensures ground
circuit does not have a voltage drop. If circuit is open,
engine may experience poor performance.
* Terminal "B" of the 4-wire connector is the by-pass circuit.
At about 400 RPM, ECM applies 5 volts to this circuit to
switch spark timing control from module to ECM. An open or
grounded by-pass circuit will set a code 42 and the engine
will operate at base timing, plus a slight amount of advance
built into the module.
* Terminal "C" is the distributor reference High circuit. This
circuit provides the ECM with RPM and crankshaft position
information.
* Terminal "D" is the EST circuit, which triggers the module.
The ECM does not know what actual timing is, but does know
when it receives the reference signal. It will advance or
retard spark from that point. If base timing is set
incorrectly, engine spark curve will be incorrect.
SENSORS
On EST systems, the coolant temperature sensor signals ECM to
advance timing on a cold engine and return timing to programmed
advance curve as engine reaches normal operating temperature. If
engine overheats, spark is retarded to prevent detonation. During
light throttle operation, throttle position sensor input to ECM allows
for additional advance.
Spark advance is also governed by input from engine RPM and
Manifold Absolute Pressure (MAP) sensor. When MAP output voltage is
low (high vacuum), ECM gives less spark advance. More spark advance is\
given when MAP output voltage is high (low vacuum).
ELECTRONIC SPARK CONTROL (ESC) SYSTEM
All Fuel Injected Engines
The basic components of Electronic Spark Control (ESC) system\
are detonation (knock) sensor, HEI/EST distributor, ESC module and
ECM. When detonation (knock) occurs, sensor sends an electrical signal\
to ESC module. The ESC module then sends the signal voltage to the
ECM. When the ECM senses a voltage drop (to less than one volt) on the\
knock sensor signal line, spark timing will be retarded. The ECM will
retard spark timing until all signals from detonation sensor cease.
See Fig. 4 .

1 - 25 Amp
Rear Washer/Wiper
2 - 15 Amp
Radio, Cigarette Lighter
3 - 25 Amp
Blower Motor
4 - 20 Amp
Turn Signal, Back-Up Lights, Rear Window Defogger Relay
5 - 10 Amp
Dome Light, Courtesy Lights, Glove Box Light, Cargo Light,
Radio Memory, Power Mirrors, Teltak Connector
6 - 15 Amp
Hazard Warning System, Stoplights
7 - 10 Amp
Parking Lights, Headlight Warning Chime/Buzzer, Instrument
Panel Light Dimmer
8 - 7.5 Amp
Gauges, Instrument Cluster, Seat Belt Warning,
Headlight Delay, Chime Module, Overhead Console
9 - 5 Amp
Instrument Panel Illumination
10 - 25 Amp
Rear Window Defogger
11 - 30 Amp (Circuit Breaker)
Power Door Locks, Power Seats, Trailer Towing Wiring Harness
12 - 10 Amp
ETR Radio, Power Antenna
13 - Not Used (1984-87)
7.5 Amp (1988)
Transmission Control Unit
14 - 25 Amp
Headlight Delay, Horns, Security Alarm
15 - 5.5 Amp (Circuit Breaker)
Front Wiper
16 - 30 Amp (Circuit Breaker)
Power Windows
17 - 10 Amp
Clock, Security Alarm (IGN)

STE ER IN G C O LU M N S W IT C HES

1988 J e ep C hero ke e
1988 STEERING
Jeep Steering Column Switches
All Models
REMOVAL & INSTALLATION
TURN SIGNAL & HAZARD FLASHER SWITCHES
Removal & Installation
1) Place front wheels in straight-ahead position. Disconnect
battery negative cable. Remove the steering wheel. Refer to the
STEERING WHEEL & HORN REMOVAL article.
2) On models with A/T, place selector lever in "PARK"
position. Remove selector lever retaining pin and lever. Using 2
screwdrivers, remove lock plate cover. On models with tilt column,
remove tilt lever.
3) Using Plate Compressor (J-23653-A), compress lock plate.
If shaft has metric threads, use Metric Forcing Screw (J-23653-4)
prior to installing compressor on shaft. Remove and discard lock plate
snap ring. Remove plate compressor
NOTE: The lock plate is under strong spring tension. DO NOT
attempt to remove snap ring without using lock plate
compressor.
4) Remove lock plate, canceling cam, upper bearing preload
spring, spring seat and bearing race (thrust washer on some models).
Depress hazard warning switch while unscrewing from column.
5) On vehicles with A/T, use a paper clip to compress lock
tab retaining shift quadrant light wire in connector block. Disconnect
wire. On all models, remove turn signal lever attaching screw and
lever.
6) On vehicles with cruise control, disconnect 2 of 4 wires
at switch connector. Fold wires back along harness. Tape wires to
harness. Tape a string to harness to aid in removal.
7) Disconnect turn signal switch wire harness at bottom of
steering column. Tape around turn signal switch harness connector to
aid in removal. Remove turn signal switch attaching screws. Remove
switch. To install, reverse removal procedure.
LOCK CYLINDER
Removal
1) Remove horn button and steering wheel. Refer to the
STEERING WHEEL & HORN REMOVAL article. Remove turn signal switch.
Remove key warning buzzer switch and contacts as an assembly, using
needle-nose pliers.
2) On models with standard column, turn ignition lock
cylinder (clockwise) 2 detent positions beyond the "OFF/LOCK"
position. On models with tilt column, turn lock cylinder to "LOCK"
position. On all models, compress lock cylinder retaining tab and
remove lock cylinder from housing. See Fig. 1.

STE ER IN G C O LU M N

1988 J e ep C hero ke e
1988 STEERING
Jeep Steering Columns
All Models
DESCRIPTION
All models use collapsible steering columns. All columns have
integral ignition switch and locking device. Optional tilt wheel is
available with both A/T and M/T. Transmission shift linkage is
integral on all models except those with floor shift.
TROUBLE SHOOTING
Refer to TROUBLE SHOOTING - BASIC PROCEDURES article in the
GENERAL TROUBLE SHOOTING section.
REMOVAL & INSTALLATION
NOTE: Steering column removal and installation procedures refer to
all manufacturers. Not all procedures, however, apply to all
models.
STEERING COLUMN (COLUMN SHIFT)
Removal
1) Disconnect battery negative cable. Disconnect transmission
shift cable rod by prying rod from grommet in shift lever. Remove
cable clip. Remove cable from lower bracket.
2) Disconnect, as equipped, either the flexible coupling,
"Pot" coupling or "U" joint from pinion shaft.
3) Disconnect wiring connectors at column jacket. Remove
steering wheel and horn pad. See STEERING WHEEL & HORN REMOVAL
article. Remove damper assembly (if equipped). On RWD models, remove
turn signal lever.
4) On all models, remove steering column-to-floor pan
attaching screws. Expose steering column bracket. Remove instrument
panel steering column cover. Lower reinforcement. Disconnect bezel.
Remove indicator set screw and gearshift pointer from shift housing.
5) Remove steering column bracket-to-instrument panel
attaching nuts. Lower support bracket. Firmly grasp steering column
assembly and pull rearward while disconnecting lower stub shaft from
pinion shaft coupling.
NOTE: On vehicles equipped with cruise control and M/T, take care
not to damage clutch pedal cruise control switch.

* The lock inhibitor assembly consists of a lever that engages
lock levers (preventing locking of steering shaft), a button
to operate lever and a return spring. Assembly is attached to
lock housing in same location as shift gate is on column
shift. Lower steering shaft bearing is mounted in an aluminum
support.
* A spring is attached between shift housing and column jacket.
This spring keeps housing rotated counterclockwise against
rubber bumper.
OVERHAUL
STANDARD COLUMN
NOTE: All columns are similar except for appearance of covers.
Some models use ignition key light, while others do not.
Disassembly and reassembly procedures cover all models. Some
procedures may not apply to every steering column.
Disassembly
1) Pry out wiring trough retainers. Lift off trough. New
retainers may be required for reassembly. Use masking tape to protect
paint and a deep socket to back-up housing. Drive retaining roll pin
out with a punch to remove shift lever.
2) Remove breakaway capsules. Secure column in vise by
clamping at column bracket. DO NOT distort column. Remove turn signal
lever cover-to-lock housing attaching screws. Remove cover. Remove
wiper/washer switch assembly. Pull switch cover up wiper/washer lever.
Remove lever sleeve-to-switch attaching screws.
3) Rotate wiper/washer shaft to full clockwise position.
Remove shaft from switch. Remove turn signal switch and upper bearing
retaining screws. Remove retainer. Lift switch upward out of way.
Unclip horn ground wire. Remove ignition key light retaining screw.
Lift ignition key light out of way.
4) Remove bearing housing-to-lock attaching screws. Remove
snap ring from upper end of steering shaft. Remove bearing housing
from shaft. Remove lock plate spring and lock plate from shaft. Remove
shaft through lower end of column.
5) Remove ignition key. Remove warning switch retaining
screw. Lift out key warning switch. Remove 2 ignition switch-to-column
jacket retaining screws. See Fig. 2. Remove ignition switch by
rotating switch 90 degrees on actuator rod. Remove 2 dimmer switch
retaining screws. Disengage dimmer switch from rod.