1988 JEEP CHEROKEE fuse
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![JEEP CHEROKEE 1988 Service Repair Manual \
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AIR RIDE SUSPENSION - WARNING LAMPS
AIR RIDE SU](/manual-img/16/57037/w960_57037-1139.png "JEEP CHEROKEE 1988 Service Repair Manual \
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AIR RIDE SUSPENSION - WARNING LAMPS
AIR RIDE SU")
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AIR RIDE SUSPENSION - WARNING LAMPS
AIR RIDE SUSPENSION - WARNING LAMP INSPECTION \
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Condition Code Procedure
Bulb burned out ......... A ............ Require replacement.
Warning light does
not come on during
bulb check ............. .. . Further inspection required to
determine cause.
Warning light flashes ... .. . Further inspection required to
determine cause.
Warning light is
intermittent ........... .. . Further inspection required to
determine cause.
Warning light stays
on after initial
bulb check ............. .. . Further inspection required to
determine cause.
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AIR RIDE SUSPENSION - WIRING HARNESSES
AIR RIDE SUSPENSION - WIRING HARNESS INSPECTION \
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Condition Code Procedure
Connector bent .......... A .. Require repair or replacement.
Connector broken ........ A .. Require repair or replacement.
Connector loose ......... A .. Require repair or replacement.
Damaged (cut, burned, or
chafed) ................ A .. Require repair or replacement.
Excessive resistance .... B .. Require repair or replacement.
Fuse blown .............. A ............ Require replacement.
Fusible link blown ...... A ............ Require replacement.
Open .................... A .. Require repair or replacement.
Poor ground ............. A .. Require repair or replacement.
Routed incorrectly ...... B .. Require rerouting according to
vehicle manufacturer's
specifications.
Shorted ................. A .. Require repair or replacement.
Terminal bent ........... A .. Require repair or replacement.
Terminal broken ......... A .. Require repair or replacement.
Terminal corroded ....... A .. Require repair or replacement.
Terminal loose .......... A .. Require repair or replacement.
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BALL JOINTS
Before requiring or suggesting ball joint replacement, the
approved OEM procedure must be used to measure ball joint wear. The
measurement(s) obtained, along with the vehicle manufacturer's
specifications, must be noted on the inspection report. Some states
require that these measurements also appear on the invoice.
NOTE: The term "perceptible movement," defined as any visible
movement in any direction, has been the industry standard
for determining the need for replacement of follower ball
joints. Some vehicle manufacturers are now publishing
specifications for follower ball joints that were
Page 1223 of 1378
![JEEP CHEROKEE 1988 Service Repair Manual ALTERNATOR article \
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\](/manual-img/16/57037/w960_57037-1222.png "JEEP CHEROKEE 1988 Service Repair Manual ALTERNATOR article \
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ALTERNATOR article \
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Alternator Blown fuse See WIRING DIAGRAMS
Light Stays Off
With Ignition
Switch ON
Defective alternator See Testing in
ALTERNATOR article
Defective indicator light See Indicator Warning
bulb or socket Lights in STANDARD
INSTRUMENTS in the
ACCESSORIES &
EQUIPMENT section
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Alternator Short in alternator wiring See On-Vehicle Tests
Light Stays OFF in ALTERNATOR article
With Ignition
Switch ON
Defective rectifier bridge See Bench Tests in
ALTERNATOR article
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Lights or Fuses Defective alternator wiring See On-Vehicle Tests
Burn Out in ALTERNATOR article
Frequently
Defective regulator See Regulator Check in
ALTERNATOR article
Defective battery Check and replace as
necessary
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Ammeter Gauge Loose or worn drive belt Check alternator drive
Shows Discharge belt tension and
condition. See Belt
Adjustment in TUNE-UP
article in the
TUNE-UP section
Defective wiring Check all wires and
wire connections
Defective alternator or See Bench Tests and
regulator On-Vehicle Tests in
ALTERNATOR article
Defective ammeter, or See Testing in
improper ammeter wiring STANDARD INSTRUMENTS
connection in the ACCESSORIES &
EQUIPMENT section
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Noisy Loose drive pulley Tighten drive pulley
Alternator attaching nut
Loose mounting bolts Tighten all alternator
mounting bolts
Worn or dirty bearings See Bearing
Replacement
ALTERNATOR article
Page 1230 of 1378
![JEEP CHEROKEE 1988 Service Repair Manual Fires With Key Flywheel runout contributes
released. Engine to the intermittent nature
Fires and Cranks
Normally
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\](/manual-img/16/57037/w960_57037-1229.png "JEEP CHEROKEE 1988 Service Repair Manual Fires With Key Flywheel runout contributes
released. Engine to the intermittent nature
Fires and Cranks
Normally
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Fires With Key Flywheel runout contributes
released. Engine to the intermittent nature
Fires and Cranks
Normally
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AIR CONDITIONING & HEAT
AIR CONDITIONING TROUBLE SHOOTING
WARNING: This is GENERAL information. This article is not intended
to be specific to any unique situation or individual vehicle
configuration. The purpose of this Trouble Shooting
information is to provide a list of common causes to
problem symptoms. For model-specific Trouble Shooting,
refer to SUBJECT, DIAGNOSTIC, or TESTING articles available
in the section(s) you are accessing.
BASIC AIR CONDITIONING TROUBLE SHOOTING CHART
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CONDITION POSSIBLE CAUSE \
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Compressor Not Working
Compressor clutch circuit open.
Compressor clutch coil inoperative.
Poor clutch ground connection.
Fan belts loose.
Thermostatic switch inoperative.
Thermostatic switch not adjusted.
Ambient temperature switch open.
Superheat fuse blown. \
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Excessive Noise or Vibration
Missing or loose mounting bolts.
Bad idler pulley bearings.
Fan belts not tightened correctly.
Compressor clutch contacting body.
Excessive system pressure.
Compressor oil level low.
Damaged clutch bearings.
Damaged reed valves.
Damaged compressor. \
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Insufficient or No Cooling;
Compressor Working
Expansion valve inoperative.
Heater control valve stuck open.
Low system pressure.
Blocked condenser fins.
Blocked evaporator fins.
Vacuum system leak.
Vacuum motors inoperative.
Control cables improperly adjusted.
Restricted air inlet.
Mode doors binding.
Blower motor inoperative.
Temperature above system capacity. \
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HEATER SYSTEM TROUBLE SHOOTING
NOTE: This is GENERAL information. This article is not intended
to be specific to any unique situation or individual vehicle
configuration. The purpose of this Trouble Shooting
information is to provide a list of common causes to
Page 1231 of 1378
problem symptoms. For model-specific Trouble Shooting,
refer to DIAGNOSTIC, or TESTING articles available in the
section(s) you are accessing.
BASIC HEATER SYSTEM TROUBLE SHOOTING CHART
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CONDITION POSSIBLE CAUSE \
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Insufficient, Erratic,
or No Heat
Low Coolant Level
Incorrect thermostat.
Restricted coolant flow through
heater core.
Heater hoses plugged.
Misadjusted control cable.
Sticking heater control valve.
Vacuum hose leaking.
Vacuum hose blocked.
Vacuum motors inoperative.
Blocked air inlet.
Inoperative heater blower motor.
Oil residue on heater core fins.
Dirt on heater core fins. \
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Too Much Heat
Improperly adjusted cables.
Sticking heater control valve.
No vacuum to heater control valve.
Temperature door stuck open. \
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Air Flow Changes During
Acceleration
Vacuum system leak.
Bad check valve or reservoir. \
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Air From Defroster At All
Times
Vacuum system leak.
Improperly adjusted control cables.
Inoperative vacuum motor. \
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Blower Does Not Operate
Correctly
Blown fuse.
Blower motor windings open.
Resistors burned out.
Motor ground connection loose.
Wiring harness connections loose.
Blower motor switch inoperative.
Blower relay inoperative.
Fan binding or foreign object
in housing.
Fan blades broken or bent. \
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BRAKES
BRAKE SYSTEM TROUBLE SHOOTING
NOTE: This is GENERAL information. This article is not intended
to be specific to any unique situation or individual vehicle
configuration. The purpose of this Trouble Shooting
information is to provide a list of common causes to
problem symptoms. For model-specific Trouble Shooting,
refer to SUBJECT, DIAGNOSTIC, or TESTING articles available
in the section(s) you are accessing.
Page 1255 of 1378
Excessive cylinder wear Rebore or replace
block
Excessive valve guide Worn or loose bearing
clearance
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Gap Bridged Deposits in combustion Clean combustion
chamber becoming fused chamber of deposits
to electrode
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Blistered Engine overheating Check cooling system
Electrode
Wrong type of fuel Replace with correct
fuel
Loose spark plugs Retighten spark plugs
Over-advanced ignition Reset ignition timing
timing see ENGINE PERFORMANCE
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Pre-Ignition or Incorrect type of fuel Replace with correct
Melted Electrodes fuel
Incorrect ignition timing Reset ignition timing
see ENGINE PERFORMANCE
Burned valves Replace valves
Engine Overheating Check cooling system
Wrong type of spark plug, Replace with correct
too hot spark plug, see
ENGINE PERFORMANCE
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Chipped Severe detonation Check for over-
Insulators advanced timing or
combustion
Improper gapping Re-gap spark plugs
procedure
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Rust Colored Additives in unleaded Try different fuel
Deposits fuel brand
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Water In Combus- Blown head gasket or Repair or replace
tion Chamber cracked head head or head gasket
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NOTE: Before diagnosing an electronic ignition system, ensure that
all wiring is connected properly between distributor, wiring
connector and spark plugs. Ignition problem will show up
either as: Engine Will Not Start or Engine Runs Rough.
BASIC ELECTRONIC IGNITION TROUBLE SHOOTING CHARTS
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CONDITION POSSIBLE CAUSE CORRECTION \
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Engine Won't Open circuit between Repair circuit
Start distributor and bulkhead
connector
Open circuit between Repair circuit
bulkhead connector and
Page 1307 of 1378
TU RN S IG NALS & H AZA R D F LA SH ER S
1988 J e ep C hero ke e
1988 Turn Signal & Hazard Light Systems
JEEP
DESCRIPTION
Turn signals and hazard flashers systems use a common turn
signal/hazard light switch assembly mounted within upper steering
column housing.
FLASHER LOCATIONS
Hazard
Mounted on fuse block.
Turn Signal
Mounted on fuse block.
TROUBLE SHOOTING
NOTE: Following trouble shooting is only information available
from manufacturer.
Hazard Lights (Comanche, Cherokee & Wagoneer)
If lights do not come on with hazard switch turned on, check
hazard/stop light fuse by operating stop lights. If fuse is okay,
check turn signal flasher, turn signal/hazard switch, and related
wiring. If only one hazard light does not work, check bulb.
Turn Signals (Comanche, Cherokee & Wagoneer)
If all turn signals do not work, check turn/back-up light
fuse by operating back-up lights. If fuse is okay, check turn signal
flasher, turn signal/hazard switch, and related wiring. If only one
turn signal does not work, check bulb.
TESTING
NOTE: Following trouble shooting is only information available
from manufacturer.
Hazard Indicators (Wrangler)
1) Turn ignition and hazard warning switch "ON". Check for
pulsating voltage at Light Blue (left indicator) and Dark Blue (right\
indicator) wires. If voltage is present, go to next step. If voltage
is not present, replace turn signal switch.
2) Remove bulbs for turn signal indicators. Measure
resistance across bulb terminals. If resistance is zero ohms, replace
light bulb(s). If resistance readings are not zero ohms, go to next
step.
3) Check for pulsating voltage at battery side of bulb
sockets. If voltage is present, go to next step. If voltage is not
present, repair open circuit between socket and turn signal switch
steering column connector.
4) Turn ignition off and check resistance on ground side of
bulb sockets. If resistance is zero ohms, hazard indicator circuit is
okay. If resistance reading is not zero ohms, repair open in ground
circuit.
Hazard Lights (Wrangler)
Page 1308 of 1378
1) Check operation of stop lights. If stop lights come on, go
to next step. If not, check hazard/stop light fuse. If fuse is okay,
check for voltage on battery side of hazard/stop light fuse. If
voltage is not present, repair open circuit between fusible link and
fuse block.
2) Remove hazard flasher and check for voltage on battery
side of hazard flasher at fuse block. If voltage is present, go to
next step. If voltage is not present, repair open circuit to fuse
block.
3) Measure resistance across turn signal flasher terminals.
If resistance across flasher is zero ohms, replace flasher. If
resistance is other than zero ohms, install flasher and turn ignition
on.
4) Check for voltage at Brown wire of turn signal switch
steering column connector. If voltage is present, go to next step. If
voltage is not present, repair open circuit between flasher and turn
signal switch connector.
5) Turn hazard warning switch "ON". Check for pulsating
voltage at Light Blue, Dark Blue, Yellow, and Dark Green wires. If
voltage is present, hazard light circuit is okay. If voltage is not
present, replace turn signal switch.
Turn Signals (Wrangler)
1) Turn ignition on and check operation of back-up lights. If
lights come on, go to step 3). If back-up lights do not come on, check
turn signal/back-up light fuse.
2) If fuse is okay, check for voltage at battery side of turn
signal/back-up light fuse. If voltage is not present, repair open
circuit between fuse block and ignition switch. If voltage is present,
go to next step.
3) Remove turn signal flasher and measure resistance across
flasher terminals. If resistance across flasher is zero ohms, replace
turn signal flasher. If flasher is okay, install flasher and turn
ignition on.
4) Check for voltage on battery side of flasher at fuse
block. If voltage is present, go to next step. If voltage is not
present, repair open circuit to fuse block.
5) Disconnect turn signal switch at steering column
connector. Place turn signal switch in left turn position and measure
resistance between Yellow and Purple wires. If resistance across wires
is zero ohms, replace turn signal switch. If resistance is other than
zero ohms, go to next step.
6) Place turn signal switch in right turn position and
measure resistance between Dark Green and Purple wires. If resistance
across wires is zero ohms, replace turn signal switch. If resistance
is other than zero ohms, turn signal circuit is okay.
Turn Signal Indicators (Wrangler)
1) Turn ignition on. Place turn signal switch in left turn
position and check for pulsating voltage at Light Blue wire. If
voltage is present, go to next step. If voltage is not present,
replace turn signal switch.
2) Place turn signal switch in right turn position and check
for pulsating voltage at Dark Blue wire. If voltage is not present,
replace turn signal switch. If voltage is present, go to next step.
3) Remove bulbs from turn signal indicators. Measure
resistance across bulb terminals. If resistance is zero ohms, replace
light bulb(s). If resistance readings are not zero ohms, turn ignition\
on.
4) Place turn signal switch in left and right turn position
and check for pulsating voltage at battery side of bulb sockets. If
voltage is present, go to next step. If voltage is not present, repair
open circuit between socket(s) and steering column connector.
Page 1319 of 1378
full load. The Kent-Moore J-39021 is such a tool, though there are
others. The Kent-Moore costs around $240 at the time of this writing
and works on many different manufacturer's systems.
The second method is to use a lab scope. Remember, a lab
scope allows you to see the regular operation of a circuit in real
time. If an injector is having an short or intermittent short, the lab
scope will show it.
Checking Available Voltage At the Injector
Verifying a fuel injector has the proper voltage to operate
correctly is good diagnostic technique. Finding an open circuit on the
feed circuit like a broken wire or connector is an accurate check with
a DVOM. Unfortunately, finding an intermittent or excessive resistance
problem with a DVOM is unreliable.
Let's explore this drawback. Remember that a voltage drop due
to excessive resistance will only occur when a circuit is operating?
Since the injector circuit is only operating for a few milliseconds at
a time, a DVOM will only see a potential fault for a few milliseconds.
The remaining 90+% of the time the unloaded injector circuit will show
normal battery voltage.
Since DVOMs update their display roughly two to five times a
second, all measurements in between are averaged. Because a potential
voltage drop is visible for such a small amount of time, it gets
"averaged out", causing you to miss it.
Only a DVOM that has a "min-max" function that checks EVERY
MILLISECOND will catch this fault consistently (if used in that mode).\
The Fluke 87 among others has this capability.
A "min-max" DVOM with a lower frequency of checking (100
millisecond) can miss the fault because it will probably check when
the injector is not on. This is especially true with current
controlled driver circuits. The Fluke 88, among others fall into this
category.
Outside of using a Fluke 87 (or equivalent) in the 1 mS "min-\
max" mode, the only way to catch a voltage drop fault is with a lab
scope. You will be able to see a voltage drop as it happens.
One final note. It is important to be aware that an injector
circuit with a solenoid resistor will always show a voltage drop when
the circuit is energized. This is somewhat obvious and normal; it is a
designed-in voltage drop. What can be unexpected is what we already
covered--a voltage drop disappears when the circuit is unloaded. The
unloaded injector circuit will show normal battery voltage at the
injector. Remember this and do not get confused.
Checking Injector On-Time With Built-In Function
Several DVOMs have a feature that allows them to measure
injector on-time (mS pulse width). While they are accurate and fast to\
hookup, they have three limitations you should be aware of:
* They only work on voltage controlled injector drivers (e.g
"Saturated Switch"), NOT on current controlled injector
drivers (e.g. "Peak & Hold").
* A few unusual conditions can cause inaccurate readings.
* Varying engine speeds can result in inaccurate readings.
Regarding the first limitation, DVOMs need a well-defined
injector pulse in order to determine when the injector turns ON and
OFF. Voltage controlled drivers provide this because of their simple
switch-like operation. They completely close the circuit for the
entire duration of the pulse. This is easy for the DVOM to interpret.
The other type of driver, the current controlled type, start
off well by completely closing the circuit (until the injector pintle
opens), but then they throttle back the voltage/current for the
duration of the pulse. The DVOM understands the beginning of the pulse