1988 JEEP CHEROKEE ignition

SPA R K C O NTR O L S YSTE M

1988 J e ep C hero ke e
1988 Exhaust Emission Systems
JEEP SPARK CONTROL SYSTEMS
DESCRIPTION
Jeep vehicles use spark control devices to assist ignition
system in controlling exhaust emissions. They are Spark Control
Temperature Override (CTO) valve, Non-Linear Vacuum Regulator (NLVR)\
valve, Forward Delay Valve, Reverse Delay Valve and on 4-cylinder
engines, Vacuum Spark Control Delay Valve. System application depends
upon engine size, emissions category and vehicle model.
COOLANT TEMPERATURE SENSOR (CTS)
The coolant temperature sensor is located in the intake
manifold coolant jacket. This sensor provides a voltage signal to the
Electronic Control Unit (ECU). The ECU uses this signal to determine
engine temperature. During cold engine operation, the ECU responds by
increasing ignition advance and inhibiting EGR operation.
NON-LINEAR VACUUM REGULATOR VALVE (NLVR)
NLVR valve is used on carbureted 6.0L models. This valve
supplies vacuum advance unit with a regulated combination of manifold
and carburetor ported vacuum when engine load is low and switches to
supply only carburetor ported vacuum as load increases.
Fig. 1: Non-Linear Vacuum Regulator Valve
Courtesy of Chrysler Motors.
OPERATION

NON-LINEAR VACUUM REGULATOR VALVE
There are 2 input ports on NLVR: intake manifold vacuum and
carburetor ported vacuum. One outlet port connects to distributor
vacuum unit. At curb idle, regulated vacuum is supplied to advance
unit, when manifold vacuum is high and ported vacuum is very low. See
Fig. 1.
NLVR regulates vacuum signal so it is between these 2 vacuum
source levels at idle. As engine load increases and vacuum signal is
above 7.5 in. Hg vacuum, regulator valve switches to ported vacuum
output.
FORWARD DELAY VALVE
Some engines use this valve to improve driveability and
reduce hydrocarbon emissions. Valve functions to delay effects of
sudden increases in vacuum. This prevents sudden spark advance during
deceleration.
REVERSE DELAY VALVE
Some engines use this valve to improve cold driveability and
reduce hydrocarbon emissions. Valve is installed in vacuum line to
delay effects of manifold vacuum decrease causing retarded ignition
timing.
VACUUM ADVANCE COOLANT TEMPERATURE OVERRIDE (VA-CTO)
This valve is used on carbureted 6.0L engines to improve
driveability when engine is cold. It is located in vacuum advance
circuit. When vacuum is greater at port "4" than at port "1", air
must flow through orifice to equalize pressure. This creates
momentary delay that prevents sudden decrease in spark advance. When
vacuum is greater at port "1" than at port "4", air flows freely
through check valve and pressure is instantly equalized.
TESTING
NON-LINEAR VACUUM REGULATOR VALVE (NLVR)
Connect vacuum gauge to distributor port "DIST" on NLVR.
With engine at idle speed, a vacuum reading of 7 in. Hg vacuum should
be shown. As throttle is opened and engine speed increases, ported
vacuum level should be indicated. If not, replace NLVR. See Fig. 1.
FORWARD DELAY VALVE
1) Connect external vacuum source to port on Black (or Red)
side of delay valve. Connect vacuum gauge to port on colored side of
valve.
2) Apply a constant 10 in. Hg vacuum. Note time required for
gauge pointer to move from 0-8 in. Hg.
3) If valve fails to meet time limits, replace valve. If
valve meets specifications, install so that Black (or Red) side is
toward vacuum source.
FORWARD DELAY VALVE TIME LIMITS (1)









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Valve Color Min. Time Max Time

reading of .2 volt or less. If reading exceeds .2 volt, clean or
repair cables and connections in circuit. Connect a voltmeter at
following locations:
* Positive lead to battery positive post and negative lead
to cable clamp.
* Positive lead to battery negative post and negative lead
to cable clamp.
3) If reading is other than zero on voltmeter, clean or
repair cables and connections in circuit. Connect a voltmeter at
following location:
* Positive lead to battery positive post and negative lead
to starter solenoid lead to the field coils.
4) If reading exceeds .3 volt, clean or repair cables and
connections in circuit.
SOLENOID TEST
1) Connect a heavy jumper wire on starter relay between
battery and solenoid terminals. If engine cranks, solenoid is okay. Go
to RELAY TEST .
2) If engine does not crank, check wiring and connections
from relay to starter. Repair or replace as necessary. If engine still
fails to crank, starter is defective.
RELAY TEST
1) On automatic transmission/transaxle vehicles, put gear
selector in "NEUTRAL" or "PARK". On manual transmission/transaxle
vehicles, put gear selector in "NEUTRAL". Set parking brake and block
wheels. DO NOT remove relay connector. Using a 12-volt test light,
check for battery voltage between starter relay battery terminal and
ground.
2) Use a jumper wire on starter relay between battery and
ignition terminals. If engine cranks starter relay is good. If starter
does not crank go to next step.
3) Connect another jumper wire to starter relay between
ground terminal and ground. Repeat above test. If engine cranks,
starter relay is good. Inspect transmission linkage for improper
adjustment (automatic transmission), defective neutral safety switch
(automatic transmission) or poor ground connection between relay
housing and mounting surface.
TESTING (ON BENCH)
STARTER SOLENOID
1) With starter removed, disconnect field coil wire from
field coil terminal on starter. Using an ohmmeter, check for
continuity between solenoid and field coil terminals.
2) Check for continuity between solenoid terminal solenoid
housing. Continuity should be present in both tests. If continuity is
present, solenoid is good. If no continuity is present, replace
solenoid. Reconnect field coil wire to field coil terminal.
ARMATURE FOR SHORT CIRCUIT
Place armature in a growler and hold a thin steel blade
parallel 3/16" above core while rotating armature slowly. If armature

1) Voltage is applied to ignition switch through fuse "B" at
all times. Voltage is also applied at all times to the contact on
starter solenoid, terminal "B".
2) With ignition switch in "START" position, battery voltage
is applied from fusible link "B", to ignition switch, and to the coil
of the starter relay to ground.
3) The coil of the starter relay engages closing relay
contacts. With start relay contacts closed, battery voltage is applied
to starter solenoid. Both solenoid windings are energized.
4) The pull-in and hold-in windings work together to
magnetically pull starter gear into ring gear. At the same time the
plunger also closes solenoid switch contacts in the starter solenoid.
Full battery voltage is now applied directly to the starter motor and
it cranks the engine.
NOTE: Use the amperage draw reading after the starter motor has
obtained its maximum RPM.
TROUBLE SHOOTING
* Check the battery for a broken or cracked casing.
* Check that all connections to battery and starter are clean
and tight.
* Check electrolyte level of battery. Levels that are too high
or too low may cause poor starter motor performance.
* Check battery by measuring specific gravity of electrolyte in
each cell with a hydrometer.
NOTE: No further testing or troubleshooting procedures available
from manufacturer.
STARTER SPECIFICATIONS
STARTER MOTOR SPECIFICATIONS TABLE








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Application Specification
Cold Cranking Voltage (Minimum) ................ 9.6 Volts
Cold Cranking Amps
Cherokee & Wagoneer ........................... 350 Amps
Comanche ...................................... 120 Amps









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TORQUE SPECIFICATIONS
TORQUE SPECIFICATIONS TABLE








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Application Ft. Lbs. (N.m)
Left Side Engine Mount-to-Block .................. 40 (54)
Left Side Engine Mount-to-Bell Housing Bolt ...... 35 (47)
Left Side Engine Mount-to-Frame Sill Bolt ........ 48 (65)
Starter Mounting Bolts ........................... 37 (50)
INCH Lbs. (N.m)
Starter Relay "B+" Terminal Nut ................... 18 (2)









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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.

Fig. 1: Removing Jeep Lock Cylinder
Courtesy of Chrysler Motors
Installation
1) To install, insert key in lock cylinder. Hold cylinder
sleeve while turning key clockwise until key stops. Align lock
cylinder retaining tab with keyway in housing. Insert cylinder into
housing.
2) Push lock cylinder inward until it contacts lock sector.
Rotate cylinder to engage it with lock sector. Push lock cylinder
inward until cylinder retaining tab engages in housing groove. To
complete installation, reverse removal procedure.
IGNITION SWITCH
Removal (Cherokee, Wagoneer & Wrangler)
Remove lower instrument panel trim panel. Insert key in lock

cylinder. Turn cylinder to "OFF-UNLOCK" position. Disconnect switch
from remote rod. Disconnect harness connectors at switch. Remove
switch.
Installation
Move switch slider to "ACC" position. Engage remote rod in
switch slider. Position switch on column, taking care not to move
slider. Hold key in "ACC" position while pushing switch down slightly
to remove slack in actuator rod. Install attaching screws. Connect
harness connectors.
IGNITION SWITCH
Removal (Comanche & Grand Wagoneer)
Remove lower instrument panel trim panel. Insert key in lock
cylinder. Turn cylinder 2 positions beyond the "OFF-UNLOCK" position.
Disconnect switch from remote rod. Disconnect harness connectors at
switch. Remove switch.
Installation
Move switch slider to "ACC" position. Move switch slider back
2 clicks to "OFF-UNLOCK" position. Engage remote rod in switch slider.
Position switch on column. DO NOT move slider while positioning
switch. Install attaching screws. Connect harness connectors.
Fig. 2: Exploded View of Jeep Steering Column Switch Assemblies
Courtesy of Chrysler Motors
TROUBLE SHOOTING
Refer to TROUBLE SHOOTING - BASIC PROCEDURES article in the
GENERAL TROUBLE SHOOTING section.

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.