1988 JEEP CHEROKEE charging
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performance ............ B .. Require repair or replacement.
Terminal loose, not
affecting performance .. 1 .. Suggest repair or replacement.
Wire lead burned ........ A .. Require repair or replacement.
Wire lead conductors
exposed ................ B .. Require repair or replacement.
Wire lead open .......... A .. Require repair or replacement.
Wire lead shorted ....... A .. Require repair or replacement.
(1) - Determine cause and correct prior to repair or
replacement of part.
( 2) - Malfunctioning includes inoperative, intermittent
operation, or failure to perform all functions.
( 3) - Make sure poor sound quality is not caused by
ignition/charging system or other forms of electrical
interference.
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TRANSDUCERS
TRANSDUCER 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.
Connector broken ........ A .. Require repair or replacement.
Connector (Weatherpack
type) leaking .......... A .. Require repair or replacement.
Connector melted ........ A ........... ( 1) Require repair or
replacement.
Connector missing ....... C ............ Require replacement.
Drive mechanism damaged,
affecting performance .. A ........... ( 2) Require repair or
replacement.
Drive mechanism damaged,
not affecting
performance ............ 2 ........... ( 2) Suggest repair or
replacement.
Inoperative ............. A ........... ( 3) Require repair or
replacement.
Leaking
(vacuum/fluid/air) ..... A ............ Require replacement.
Linkage bent, affecting
performance ............ A ... Require repair or replacement
of linkage.
Linkage bent, not
affecting performance .. .. ........ No service suggested or
required.
Linkage binding, affecting
performance ............ A ... Require repair or replacement
of linkage.
Linkage binding, not
affecting performance .. 2 ... Suggest repair or replacement
of linkage.
Linkage broken .......... A ... Require repair or replacement
Page 673 of 1378
Post (top or side) burned,
affecting performance .. A ........... (6) Require repair or
replacement.
Post (top or side) burned,
not affecting
performance ............ 2 ........... ( 6) Suggest repair or
replacement.
Post (top or side)
corroded, affecting
performance ............ A ................. Require repair.
Post (top or side)
corroded, not affecting
performance ............ 2 ................. Suggest repair.
Post (top or side)
loose .................. A ............ Require replacement.
Post (top or side)
melted, affecting
performance ............ A ........... ( 6) Require repair or
replacement.
Post (top or side)
melted, not affecting
performance ............ 2 ........... ( 6) Suggest repair or
replacement.
Specific gravity low .... B .......... ( 7) Further inspection
required.
State of charge low ..... A .......... ( 7) Further inspection
required.
Top dirty ............... 2 ....... Suggest cleaning battery.
Top wet ................. A ... ( 8) Require cleaning battery.
Further inspection required.
Vent cap loose .......... A ... Require repair or replacement
of vent cap.
Vent cap missing ........ C ..... Require replacement of vent
cap.
( 1) - DO NOT attempt to charge a frozen battery. Allow
battery to warm thoroughly and then performance-test.
If battery fails performance test, require replacement.
( 2) - No service suggested or required unless the battery
fails performance test, in which case, require
replacement.
( 3) - This phrase refers to a battery that fails to either
accept and/or retain a charge using appropriate times
listed in the Battery Charging Guide of the BCI Service
Manual, battery charger operating manual, or battery
manufacturer's specifications.
( 4) - Determine cause of low fluid level. Refill to proper
level(s) with water (distilled water preferred).
Recharge battery and performance-test.
( 5) - The battery may meet battery manufacturer's
specifications but test below the minimum
specification defined by the vehicle's OEM for
that vehicle.
( 6) - Determine cause and correct prior to repair or
replacement of part.
( 7) - Recharge and test to manufacturer's specifications.
If battery fails performance test, require replacement.
( 8) - Check fluid level and adjust to manufacturer's
specification. Suggest checking charging system
for proper operation.
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BATTERY CABLES, WIRES AND CONNECTORS
Page 777 of 1378
* Battery connections and specific gravity.
* Engine Compression.
* Electrical connections on components and sensors.
* Emission control devices.
* Ignition system.
* All vacuum line, fuel hose and pipe connections.
General Precautions
In order to prevent injury to operator or damage to system
or component parts, use following techniques:
* Turn ignition off before connecting or disconnecting any
component parts.
* DO NOT apply DC voltage greater than 12 volts or any AC voltage
to system.
* Disconnect battery cables before charging.
* Remove ECU from vehicle if ambient temperature could exceed
176
F (80C).
* DO NOT modify or circumvent any system functions.
SYSTEM TESTING
Fuel System Test
WARNING: Always relieve residual fuel pressure in fuel delivery
system before opening system. To prevent chance of personal
injury, cover fittings with shop towel while disconnecting
fittings.
1) Remove cap from pressure test port located in fuel rail.
See Fig. 3 . Connect Fuel Pressure Gauge (J-34730-1) to pressure
fitting.
2) Start vehicle. Pressure should be approximately 31 psi
(2.1 kg/cm
) with vacuum hose connected to pressure regulator and
39 psi (2.6 kg/cm ) with vacuum hose removed from pressure
regulator.
3) Check fuel pump flow rate. A good fuel pump will deliver
at least one liter of fuel per minute with fuel return line pinched
off. If fuel pump does not pump adequately, inspect fuel system for a
plugged fuel filter or filter sock.
Fig. 3: Fuel System Pressure Test Components
Courtesy of Chrysler Motors.
4) Fuel pump flow rate can be checked by connecting one end
of an old A/C gauge hose to fuel test port on fuel rail and inserting
Page 798 of 1378
3) Return throttle plate to closed throttle position (M/T),
or maintain throttle plate in closed position (A/T). Check sensor
output voltage. To do so, disconnect voltmeter positive lead from
terminal "C" and connect it to terminal "A" (top) of sensor (M/T), o\
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from terminal "A" and connect it to terminal "B" (A/T).
4) Move and hold throttle plate in wide open throttle
position (M/T), or maintain throttle plate in closed position (A/T).\
Ensure throttle linkage contacts stop. Note voltmeter reading. Output
voltage should be 4.6-4.7 volts (M/T), or .2 volt (A/T).
5) If output voltage is incorrect, loosen bottom sensor
retaining screw and pivot sensor in adjustment slot for a coarse
adjustment. Loosen top sensor retaining screw for fine adjustments.
Tighten screws after adjustment.
TESTING & TROUBLE SHOOTING
PRELIMINARY CHECKS & PRECAUTIONS
Subsystem Checks
Before testing fuel injection system for cause of
malfunction, check that following subsystems and components are in
good operating condition:
* Battery and charging system.
* Engine state of tune.
* Emission control devices.
* Fuel system pressure and delivery volume.
* Wiring connectors at components.
General Precautions
In order to prevent injury to operator or damage to system
or component parts, use following techniques:
* Turn ignition off before connecting or disconnecting any
component parts.
* DO NOT apply DC voltage greater than 12 volts or any AC voltage
to system.
* Disconnect battery cables before charging.
* Remove ECU from vehicle if ambient temperature could exceed
176
F (80C).
* DO NOT modify or circumvent any system functions.
RESISTANCE & VOLTAGE TESTS
MAT Sensor
1) Disconnect wiring from MAT sensor. Using high input
impedance digital volt-ohmmeter (DVOM), check resistance of sensor.
Resistance should be less than 1000 ohms when engine is warm. Replace
sensor if it does not fall within range shown in
TEMPERATURE-TO-RESISTANCE VALUES table.
2) Test resistance in wiring harness between ECU connector
terminal No. 32 and sensor connector terminal. Also test resistance
in wiring harness between ECU harness terminal No. 14 and sensor
connector terminal. See Fig. 5. Repair wiring harness if open circuit
or resistance greater than one ohm is indicated.
Coolant Temperature Sensor (CTS)
1) Disconnect wiring harness from CTS. Using high input
impedance digital volt-ohmmeter (DVOM), check resistance of sensor.
Resistance should be less than 1000 ohms when engine is warm. Replace
sensor if it does not fall within range shown in
TEMPERATURE-to-RESISTANCE VALUES table.
Page 895 of 1378
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IN STR UM EN T P A N EL - S TA N DAR D
1988 J e ep C hero ke e
1988 Switches & Instrument Panels
JEEP
DESCRIPTION & OPERATION
Instrument panel is composed of speedometer housing,
tachometer and instrument cluster gauges.
FUEL GAUGE
System consists of a fuel gauge, an in-tank sending unit, and
appropriate wiring. Fuel gauge is grounded through variable resistor
of sending unit. A float attached to a slide rheostat follows fuel
level and varying resistance increases or decreases indicator reading.
TEMPERATURE GAUGE
System consists of gauge and sending unit and appropriate
wiring. The gauge is grounded through variable resistor of sending
unit. Changes in coolant temperature vary resistance in sending unit,
increasing or decreasing indication on gauge.
VOLTMETER
The voltmeter indicates regulated voltage to provide an
indication of charging system's ability to maintain battery charge.
OIL PRESSURE GAUGE
The oil pressure gauge system consists of gauge and a
variable resistance sending unit. Gauge needle, attached to bi-
metallic strip, responds to temperature changes.
REMOVAL & INSTALLATION
INSTRUMENT CLUSTER
Removal & Installation
1) Disconnect negative battery cable. On models with cruise
control, reach behind instrument cluster and disconnect speedometer
cable from speed switch. See Fig. 1.
2) On models without cruise control, raise vehicle on hoist.
Disconnect speedometer cable from transfer case (or transmission) and
at frame rail bracket. Move speedometer cable forward and upward to
provide slack. Lower vehicle.
3) On all models, remove instrument panel bezel screws and
bezel. Remove screws attaching cigarette lighter and switch housings
to instrument panel. Move housings aside.
4) Remove screws attaching cluster to instrument panel and
carefully pull cluster and speedometer toward rear of vehicle.
Disconnect wiring harness connectors.
5) Squeeze speedometer cable locking tabs and disconnect
cable from speedometer. See Fig. 1. Remove instrument cluster. To
install, reverse removal procedure.
Page 1222 of 1378
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TR O UBLE S H O OTIN G - B ASIC P R O CED URES
1988 J e ep C hero ke e
GENERAL TROUBLE SHOOTING
* PLEASE READ THIS FIRST *
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.
ACCESSORIES & ELECTRICAL
CHARGING 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.
BASIC CHARGING SYSTEM TROUBLE SHOOTING CHART
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CONDITION POSSIBLE CAUSE CORRECTION \
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Vehicle Will Not Dead battery Check battery cells,
Start alternator belt
tension and alternator
output
Loose or corroded battery Check all charging
connections system connections
Ignition circuit or switch Check and replace as
malfunction necessary
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Alternator Light Loose or worn alternator Check alternator drive
Stays On With drive belt tension and
Engine Running condition, See Belt
Adjustment in TUNE-UP
article in the
TUNE-UP section
Loose alternator wiring Check all charging
connections system connections
Short in alternator light See Indicator Warning
wiring Lights in STANDARD
INSTRUMENTS in the
ACCESSORIES &
EQUIPMENT section
Defective alternator stator See Bench Tests in
or diodes ALTERNATOR article
Defective regulator See Regulator Check in
Page 1224 of 1378
![JEEP CHEROKEE 1988 Service Repair Manual Defective diodes or stator See Bench Test in
ALTERNATOR article
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\](/manual-img/16/57037/w960_57037-1223.png "JEEP CHEROKEE 1988 Service Repair Manual Defective diodes or stator See Bench Test in
ALTERNATOR article
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Defective diodes or stator See Bench Test in
ALTERNATOR article
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Battery Does Loose or worn drive belt Check alternator drive
Stay Charged belt tension and
condition. See
Belt Adjustment in
appropriate TUNE-UP
article in the
TUNE-UP section
Loose or corroded battery Check all charging
connections system connections
Loose alternator connections Check all charging
system connections
Defective alternator or See On-Vehicle Tests
battery and Bench Tests in
ALTERNATOR article
Add-on electrical accessories Install larger
exceeding alternator capacity alternator
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Battery Defective battery Check alternator
Overcharged- output and repair as
Uses Too Much necessary
Water
Defective alternator See On-Vehicle Test and
Bench Tests in
ALTERNATOR article
Excessive alternator voltage Check alternator output
and repair as necessary
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IGNITION 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.
Ignition Secondary Trouble Shooting Chart
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START: Visually inspect Spark Plug Wires, Coil Wires,
Plug Wire Boots, Rotor, and Distributor Cap for
signs of damage.
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OK NOT OK
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* To test secondary ignition * Repair or replace
system, modify a Spark Plug damaged components
by attaching a ground wire as necessary
to the body of the plug and
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