1988 JEEP CHEROKEE ignition

system will store a diagnostic trouble code in the TCM memory if
certain electronic problems exist. If electronic problem goes away,
diagnostic trouble code will be erased from TCM memory after ignition
has been cycled approximately 75 times.
NOTE: Diagnostic trouble code may be referred to as fault code.
Diagnostic trouble codes can be retrieved using a Diagnostic
Readout Box-II (DRB-II). After repairing an electrical system problem,\
stored diagnostic trouble code must be cleared from TCM memory.
The TCM is located behind right side of instrument panel on
Cherokee. See Fig. 1.
Fig. 1: Transmission Control Module (TCM) I.D. (Cherokee)
Courtesy of Chrysler Corp.
VALVE BODY SOLENOIDS
Valve body solenoids, mounted on the valve body, are output
devices controlled by signals received from the TCM. See Fig. 2. The
No. 1 and 2 valve body solenoids control transmission shifts while the
No. 3 valve body solenoid is used for torque converter lock-up.
When No. 1 and 2 valve body solenoids are energized,
solenoid plunger moves from seat. This opens the drain port and
releases line pressure. When either valve body solenoid is de-
energized, plunger closes the drain port.
The No. 3 valve body solenoid operates in reverse. When No. 3
valve body solenoid is de-energized, solenoid plunger moves away from
seat. This opens the drain port and releases line pressure. When No. 3
valve body solenoid is energized, the plunger closes the drain port.

DRB-II scan tool. When retrieving diagnostic trouble codes
using DRB-II, you must first enter AW4 MENU and then
retrieve diagnostic trouble codes.
NOTE: Ensure TEST 1A - VERIFICATION OF THE COMPLAINT is performed
when trouble shooting the vehicle. This test checks for
diagnostic trouble codes with vehicle stationary and during
road test. See TEST 1A - VERIFICATION OF THE COMPLAINT under
TROUBLE SHOOTING CHARTS.
NOTE: The DRB-II scan tool can be used in several different modes
using manufacturer's instructions to activate system
components and perform several tests on transmission. See
DRB-II OPERATING MODES .
Entering AW4 MENU
1) Ensure ignition is off. Connect DRB-II to 6-pin
transmission diagnostic connector. See Fig. 3. Transmission diagnostic
connector is located to the right of the steering column on driver's
side of instrument panel above accelerator pedal or below glove box on
passenger's side.
Fig. 3: Diagnostic Connector & Terminals I.D. (Cherokee)
Courtesy of Chrysler Corp.
2) Turn ignition on. Copyright date and diagnostic program
will be briefly displayed. If DRB-II displays an error message,
proceed to DRB-II PROBLEMS & ERROR MESSAGES . The following are
possible error messages that may appear.

Park ........................................... "B" & "C"
Reverse ........................................ "A" & "E"
Neutral ........................................ "B" & "C"
Drive ................................................ (1)
3 .............................................. "A" & "G"
1-2 ............................................ "A" & "H"
( 1) - No continuity should exist between any terminals.









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Fig. 4: Identifying Neutral Safety Switch Terminals
Courtesy of Chrysler Corp.
SPEED SENSOR
1) Disconnect electrical connector at speed sensor located on
adapter housing or extension housing. Connect ohmmeter leads between
speed sensor electrical terminals.
2) Rotate transmission output shaft and note ohmmeter
reading. Ohmmeter needle should fluctuate to indicate speed sensor
operation. Replace speed sensor if no reading is obtained.
THROTTLE POSITION SENSOR (TPS)
NOTE: Digital voltmeter must be used to check TPS.
1) Note location of TPS electrical connector. See Fig. 5.
Turn ignition on. Using digital voltmeter, check output voltage at
center terminal with throttle plate closed (idle position) and wide
open (full throttle).
2) With throttle plate closed (idle position), output voltag\
e
should be greater than 200 millivolts. With throttle plate wide open
(full throttle), output voltage should be less than 4.8 volts.
3) Ensure output voltage gradually increases as throttle
plate is moved from closed to wide open throttle. If no voltage
exists, check for defective wiring circuits or connections. Replace
TPS if defective.

This test verifies the correct operation of the AW4
transmission. It must be performed after finding no faults using the
DRB-II, and after a vehicle repair has been made.
1) Turn ignition key to "OFF".
2) Hold the MODE key and press the ATM key on the DRB-II at
the same time to restart the DRB-II.
3) Turn ignition key to "ON".
4) Reconnect all previously disconnected connectors.
5) Verify that the AW4 transmission control unit is properly
mounted.
6) Make sure the transmission fluid is at the proper level.
Check the fluid with the transmission temperature hot, the vehicle on
level ground, and the gear selector in neutral.
7) If any repairs have been made, test the vehicle as
instructed in TEST 1A - VERIFICATION OF THE COMPLAINT , and read faults
using the DRB-II. If there are any fault messages present, repeat TEST
1A - VERIFICATION OF THE COMPLAINT.
TEST 3A - STORED DIAGNOSTIC TROUBLE CODES TEST
NOTE: Perform TEST 1A - VERIFICATION OF THE COMPLAINT
before proceeding.
1) At this point, the Visual Inspection has been performed, a
"FAULT STORED" code has been found and the vehicle has been test
driven. The fault code is not "FAULT PRESENT", so it cannot be
considered a CURRENT or HARD fault.
2) All solenoid circuits are in the same harness and a common
ground wire is used for the solenoids. Use the following figures to
identify the harness and connector to inspect. See Fig. 7 and 8. if
all 3 solenoid faults are present, repair the Black wire (Cherokee)
ground wire open condition.
3) Carefully inspect the entire suspected circuit. Pay
particular attention to connectors, corrosion, accident damage, and
improper or missing parts.
4) If any problems are found, make the appropriate repair.
Then perform TEST 1A using the DRB-II.
5) Erase fault codes.
6) If no problems are found, perform the SYSTEM TEST using
the DRB-II. Re-check for fault codes. If there are no fault codes,
perform TEST 2A - VERIFICATION TEST . If fault code(s) return, perform
TEST 1A - VERIFICATION OF THE COMPLAINT .
Fig. 7: Test 3A - Location of 7-Way Connector

TPS cannot be rotated, reinstall TPS with end of throttle
shaft on other side of TPS socket tangs.
Fig. 128: Installing Throttle Position Sensor (TPS)
Courtesy of Chrysler Corp.
TRANSMISSION CONTROL MODULE (TCM)
Removal & Installation (Cherokee)
Ensure ignition is off. Disconnect electrical connector from
TCM, located behind right side of instrument panel. See Fig. 129.
Remove fastener and TCM from instrument panel. To install, reverse
removal procedure.
Fig. 129: Transmission Control Module (TCM) I.D. (Cherokee)
Courtesy of Chrysler Corp.
VALVE BODY SOLENOID

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* B RAK E S YSTE M U NIF O RM IN SPEC TIO N G UID ELIN ES *

1 988 J e ep C hero ke e
GENERAL INFORMATION
Brake Systems - Motorist Assurance Program
Standards For Automotive Repair
All Makes & Models
CONTENTS
OVERVIEW OF MOTORIST ASSURANCE PROGRAM
OVERVIEW OF SERVICE REQUIREMENTS AND SUGGESTIONS
ACCELEROMETERS (G SENSOR OR LATERAL)
ACCUMULATORS
ANCHOR PINS
ANTI-LOCK BRAKE SYSTEMS
BACKING PLATES
BRAKE FLUID
BRAKE FRICTION MATERIAL
BRAKE PADS
BRAKE PEDALS
BRAKE SHOES
BRAKE SHOE HARDWARE
BRAKE STOPLIGHT SWITCHES
BULB SOCKETS
BULBS AND LEDS
CALIPER HARDWARE
CALIPERS
CONTROLLERS
DIGITAL RATIO AXLE CONTROLLERS AND BUFFERS (DRAC AND DRAB)
DISABLE SWITCHES
DRUMS
ELECTRICAL PUMPS AND MOTORS
ELECTRONIC CONTROLLERS
FLUID
FLUID LEVEL SENSOR SWITCHES
FOUR WHEEL DRIVE SWITCHES
FRICTION MATERIAL
G SENSORS
HOSES
HYDRAULIC MODULATORS
HYDRO-BOOSTERS
HYDRO-ELECTRIC BOOSTERS (POWERMASTER)
IGNITION DISABLE SWITCHES
LATERAL ACCELERATION SWITCHES
LEDS
LENSES
MASTER CYLINDERS
MODULATORS
MOTORS
PARKING BRAKE SWITCHES
PARKING BRAKE SYSTEMS
PADS
PEDAL TRAVEL SWITCHES
PEDALS
POWERMASTER
PUMPS
PRESSURE DIFFERENTIAL SWITCHES
PRESSURE SWITCHES
RELAYS
ROTORS
SELF-ADJUSTING SYSTEMS

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HYDRO-BOOSTERS
NOTE: Hydro-boosters and hydro-electric boosters are combined.
HYDRO-BOOSTER 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 replacement.
Connector missing ....... C ............ Require replacement.
Does not apply assist, or
inadequate assist ...... A .. Require repair or replacement.
Leaking ................. B .. Require repair or replacement.
Leaks fluid at fitting .. B ........... Require tightening or
replacement.
Leaks fluid at unit ..... B .. Require repair or replacement.
Leaks fluid from pressure
hose(s) ................ B . Require replacement of hose(s).
Leaks fluid into passenger
compartment ............ B .. Require repair or replacement.
Threads damaged ......... A .. Require repair or replacement.
Terminal burned, affecting
performance ............ A ........... ( 1) Require repair or
replacement.
Terminal burned, not
affecting performance .. 2 .. Suggest repair or replacement.
Terminal corroded,
affecting performance .. A .. Require repair or replacement.
Terminal corroded, not
affecting performance .. 2 .. Suggest repair or replacement.
Terminal loose, affecting
performance ............ B .. Require repair or replacement.
Terminal loose, not
affecting performance .. 1 .. Suggest repair or replacement.
Threads stripped (threads
missing) ............... A ............ Require replacement.
( 1) - Determine cause and correct prior to replacement of part.









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HYDRO-ELECTRIC BOOSTERS (POWERMASTER)
See HYDRO-BOOSTERS .
IGNITION DISABLE SWITCHES
See SWITCHES.

control module before starting diagnosis or repair procedure, as this
connection is disturbed when Cruise Command System Tester (AM PC-1-R)
is used. Poor connection at this point may be improperly diagnosed as
control module malfunction.
Brake light and clutch switches should be properly adjusted.
Ensure that all vacuum lines are correctly routed and tightly
connected.
CRUISE COMMAND SYSTEM TESTS
Testing is performed with Cruise Command System Tester (AM
PC-1-R). Remove wire harness connector from control module. Connect
tester to wire harness connector. Perform tests as part of service
diagnosis to determine cause and correction of system malfunction.
Various tester lights are associated with specific components,
circuits, etc.
CONTROL SWITCH CONTINUITY
Wrangler
NOTE: Voltage checks should show battery voltage. If resistance
readings are incorrect, check circuit for an open or a
short. Cruise control module terminal No. 1 grounds through
connector at engine block.
Light No. 1 "OFF" (Set Switch)
With control switch in "ON" position, check for battery
voltage between HAZ/STOP and in-line fuse, terminal No. 14 and ground
terminal No. 1
Light No. 2 "OFF" (Control Switch & Speed Sensor)
With control switch in "ON" position, check for battery
voltage between HAZ/STOP and in-line fuse, terminal No. 5 and ground
terminal No. 1. With ignition switch in "OFF" position, check
resistance between terminals No. 2 and No. 3. Resistance should be 15-
50 ohms.
Light No. 3 "OFF" (Brake Light Ground)
With ignition switch in "ON" position, install jumper wire
between terminals No. 7 and No. 13. If brake lights do not turn on,
check fuses and brake light switch connections.
Light No. 4 "OFF" (Throttle Position Feedback Sensor)
With ignition switch in "ON" position, check for battery
voltage between gauge fuses at terminals No. 7 and No. 1.
With ignition switch in "OFF" position, check resistance
between terminals No. 2 and No. 11. Resistance should be 2400-4000
ohms. At idle resistance should be 2800-4300 ohms and at wide open
throttle resistance should be 4000 ohms.
Light No. 5 "OFF" (Resume/Accel/Vent Valve)
With control switch in "RESUME/ACCEL" position, check for
battery voltage between HAZ/STOP and in-line fuse, terminal No. 10 and
ground terminal No. 1. With ignition switch in "OFF" position, check
resistance between terminals No. 6 and No. 12. Resistance should be
30-50 ohms. Resistance between terminals No. 6 and ground, and
terminal No. 12 and ground should be infinite (open).
Light No. 6 "OFF" (Resume/Accel/Charge Valve)
With control switch in "RESUME/ACCEL" position, check for
battery voltage between HAZ/STOP and in-line fuse, terminal No. 10 and
ground terminal No. 1. With ignition switch in "OFF" position, check
resistance between terminals No. 4 and No. 12. Resistance should be