1988 JEEP CHEROKEE lock

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AU TO T R AN S D IA G NO SIS - A W 4

1988 J e ep C hero ke e
AUTOMATIC TRANSMISSIONS
Aisin Warner 4 Electronic Diagnosis
APPLICATION
NOTE: Transmission may also be referred to as AW-4.
TRANSMISSION APPLICATION









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Vehicle Application Transmission Model
Jeep
1987-96 Cherokee ................................... AW4
1987-92 Comanche ................................... AW4
1987 Grand Wagoneer ................................ AW4
1987-90 Wagoneer ................................... AW4
1992 Wrangler ...................................... AW4









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NOTE: Vehicle body code may be required when diagnosing or
repairing transmission, as body code may be used instead of
vehicle model name. See BODY CODE DESIGNATION table.
BODY CODE DESIGNATION









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Vehicle Model Body Code
Cherokee .............................................. XJ
Comanche .............................................. MJ
Grand Wagoneer ........................................ SJ
Wagoneer .............................................. XJ
Wrangler .............................................. YJ









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DESCRIPTION
The electronic control system for the AW-4 transmission
controls transmission shift points and torque converter lock-up.
Electronic control system consists of Transmission Control Module
(TCM), valve body solenoids, throttle position sensor, speed sensor,
neutral safety switch and brake switch.
NOTE: Transmission Control Module (TCM) may be referred to as
Transmission Control Unit (TCU). Neutral safety switch may
be referred to as park/neutral safety switch or gear select
switch.
OPERATION
TRANSMISSION CONTROL MODULE (TCM)
The TCM determines shift points and torque converter lock-up
based on input signals received from throttle position sensor, neutral
safety switch, speed sensor and brake switch. The TCM controls
transmission shift points and torque converter lock-up by operating
electric solenoids mounted on the valve body.
The TCM contains a self-diagnostic system used for
determining an electronic component failure. The TCM self-diagnostic

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.

NOTE: For valve body solenoid usage, see VALVE BODY SOLENOID
APPLICATION table.
VALVE BODY SOLENOID APPLICATION (1)









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Shift Lever No. 1 No. 2
Position Solenoid Solenoid
"D" (Drive)
1st Gear .................. ON .................... OFF
2nd Gear .................. ON ..................... ON
3rd Gear .................. OFF .................... ON
4th Gear .................. OFF ................... OFF
"3"
1st Gear .................. ON .................... OFF
2nd Gear .................. ON ..................... ON
3rd Gear .................. OFF .................... ON
"1-2"
1st Gear .................. ON .................... OFF
2nd Gear .................. ON ..................... ON
"R" (Reverse) .............. ON .................... OFF
"N" Or "P" ................. ON .................... OFF
( 1) - Valve body contains 3 valve body solenoids. See
Fig. 2. No. 1 and 2 valve body solenoids are used
for controlling transmission shifts. No. 3 valve
body solenoid is used for torque converter
lock-up only.









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Fig. 2: Identifying Valve Body Solenoids
Courtesy of Chrysler Corp.
BRAKE SWITCH

Brake switch is an input device mounted above the brake
pedal. When brake pedal is operated, brake switch delivers an input
signal to the TCM. The TCM uses input signal for controlling No. 3
valve body solenoid for torque converter lock-up.
NEUTRAL SAFETY SWITCH
NOTE: Neutral safety switch may be referred to as park/neutral
safety switch or gear select switch.
Neutral safety switch is an input device mounted on the
transmission manual valve shaft. Neutral safety switch delivers an
input signal to TCM, indicating transmission manual valve gear
position.
SPEED SENSOR
Speed sensor, mounted in adapter housing or extension
housing, is an input device consisting of speed sensor rotor and speed
sensor. Speed sensor rotor is mounted on transmission output shaft.
Input signal is delivered from speed sensor to TCM with each
revolution of transmission output shaft. The TCM uses input signal for
controlling transmission operation.
THROTTLE POSITION SENSOR (TPS)
The TPS, mounted on throttle body, determines throttle
position and delivers an input signal to TCM. The TCM uses input
signal for controlling transmission upshifts and torque converter
lock-up.
SELF-DIAGNOSTIC SYSTEM
DIAGNOSTIC PROCEDURE
When performing vehicle diagnosis:
* Ensure transmission fluid level is correct and fluid is
neither contaminated nor aerated.
* Ensure shift cable is properly adjusted. Refer to the
appropriate TRANSMISSION SERVICING - A/T article in
this section.
* Ensure battery is fully charged.
* Perform visual inspection, ensuring all electrical
connections at transmission, TCM, throttle position sensor,
neutral safety switch, speed sensor and brake switch are
clean and properly installed.
* Perform TEST 1A - VERIFICATION OF THE COMPLAINT under TROUBLE
SHOOTING CHARTS in this article.
* Repair diagnostic trouble codes in order displayed.
* Always perform TEST 2A - VERIFICATION TEST after repair is
completed. See TEST 2A - VERIFICATION TEST under TROUBLE
SHOOTING CHARTS in this article.
RETRIEVING DIAGNOSTIC TROUBLE CODES
NOTE: Manufacturer recommends using Chrysler's Diagnostic Readout
Box-II (DRB-II) with proper cartridge for system diagnosis.
Other after-market scan tools may be used for system
diagnosis. The following procedure is for DRB-II scan tool
usage. Use manufacturer's instruction for operating the

volts, check charging system.
KEYPAD TEST FAILURE
1) If KEYPAD TEST FAILURE message is displayed, disconnect
DRB-II from transmission diagnostic connector. DO NOT touch keys on
DRB-II keypad. Reconnect DRB-II to transmission diagnostic connector
and note display.
2) If KEYPAD TEST FAILURE message is not displayed, proceed
with diagnostics. If KEYPAD TEST FAILURE message is displayed, replace
DRB-II and proceed with diagnostics.
LOW BATTERY
If LOW BATTERY message is displayed, use external voltmeter
to check battery voltage at battery terminals. If battery voltage is
11.7-13.0 volts, replace DRB-II. If battery voltage is not 11.7-13.0
volts, check charging system.
RAM TEST FAILURE
1) If RAM TEST FAILURE message is displayed, disconnect DRB-
II from transmission diagnostic connector. DO NOT touch keys on DRB-II
keypad. Reconnect DRB-II to transmission diagnostic connector and note
display.
2) If RAM TEST FAILURE message is not displayed, proceed with
diagnostics. If RAM TEST FAILURE message is displayed, replace DRB-II
and proceed with diagnostics. If KEYPAD TEST FAILURE message is
displayed, replace DRB-II and proceed with diagnostics.
COMPONENT TESTING
BRAKE SWITCH
Brake switch is mounted above brake pedal. When brake pedal
is operated, brake switch delivers an input signal to TCM. The TCM
uses input signal for controlling No. 3 valve body solenoid for torque
converter lock-up. No other information is available from
manufacturer.
NOTE: For proper brake switch adjustment, see BRAKE SWITCH under
REMOVAL & INSTALLATION .
NEUTRAL SAFETY SWITCH
NOTE: Neutral safety switch may be referred to as park/neutral or
gear select switch. For proper neutral safety switch
adjustment, see NEUTRAL SAFETY SWITCH under REMOVAL &
INSTALLATION.
Disconnect electrical connector. Note terminal
identification. See Fig. 4. Using ohmmeter, check continuity between
specified terminals in relation to shift lever position. See NEUTRAL
SAFETY SWITCH CONTINUITY SPECIFICATIONS table. Replace neutral safety
switch if continuity is not as specified.
NEUTRAL SAFETY SWITCH CONTINUITY SPECIFICATIONS









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Shift Lever Continuity
Position Between Terminals

Installation
1) Install brake switch in retainer. Reconnect brake switch
electrical connector.
2) To check brake switch adjustment, slightly depress brake
pedal and note operation of brake switch plunger. Brake switch plunger
should fully extend when brake pedal free play is taken up and brake
application begins.
3) Clearance between brake switch plunger and brake pedal
should be approximately 1/8". If clearance is not within
specification, pull brake pedal rearward as far as possible.
4) Brake pedal should contact brake switch plunger, pushing
brake switch backward in retainer to provide proper adjustment. Ensure
brake lights operate.
5) Recheck clearance between brake switch plunger and brake
pedal with brake pedal depressed and free play taken up. Reinstall
lower steering column cover or trim panels.
NEUTRAL SAFETY SWITCH
NOTE: Neutral safety switch may be referred to as park/neutral or
gear select switch.
Removal
1) Apply parking brake. Raise and support vehicle. Disconnect
electrical connector at neutral safety switch. Pry lock washer tabs
away from retaining nut. See Fig. 126.
2) Remove retaining nut, lock washer and adjusting bolt. See
Fig. 126 . Remove neutral safety switch from manual valve shaft.
Installation
1) Disconnect shift control rod from transmission shift
lever. Rotate transmission shift lever fully rearward and then forward
2 detents to Neutral position.
2) Install neutral safety switch on manual valve shaft.
Install adjusting bolt but DO NOT tighten at this time.
3) Install lock washer and retaining nut. Tighten retaining
nut to specification. See TORQUE SPECIFICATIONS. DO NOT bend over lock
washer tabs at this time.
4) Ensure transmission is still in Neutral. Rotate neutral
safety switch and align neutral standard line with vertical groove on
manual valve shaft. See Fig. 126.
5) Tighten the adjusting bolt to specification. Refer to the
TORQUE SPECIFICATIONS table. Bend lock washer tabs over. Reconnect
shift control rod and electrical connector. Ensure vehicle starts in
Park and Neutral only.
Fig. 126: Installing Neutral Safety Switch
Courtesy of Chrysler Corp.
SPEED SENSOR

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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

and make an informed decision about how to proceed.
BRAKES
SERVICE PROCEDURES REQUIRED & SUGGESTED FOR PROPER
VEHICLE OPERATION
Some states may have specifications that differ from OEM.
Check your local/state regulations. Where state or local laws are
stricter, they take precedence over these guidelines.
ACCELEROMETERS (G SENSOR OR LATERAL)
ACCELEROMETER INSPECTION








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Condition Code Procedure
Broken .................. A ............ Require replacement.
Connector loose ......... A .. Require repair or replacement.
Loose ................... B .. Require repair or replacement.
Missing ................. C ............ Require replacement.
Out of position ......... B ....... Require re-positioning to
vehicle manufacturer's
specifications.
Output signal incorrect . B ............ Require replacement.









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ACCUMULATORS
ACCUMULATOR INSPECTION








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Condition Code Procedure
Leaking ................. B ............ Require replacement.
Missing ................. C ............ Require replacement.
Pre-charge incorrect .... B ............ Require replacement.









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ANCHOR PINS
See BACKING PLATES .
ANTI-LOCK BRAKE SYSTEMS
NOTE: Anti-lock brakes are an integral part of the brake system. It
is essential that the anti-lock brakes function properly when
brake service is performed.
Anti-lock brake systems are commonly referred to as "ABS" and
will be referred to as "ABS" throughout these guidelines. Some ABS
components also function as part of a traction control system (TCS).
WARNING: When diagnosing and servicing high pressure components,
observe safety procedures and equipment requirements
established by the vehicle manufacturer to reduce the
possibility of serious personal injury.
NOTE: Intermittent electrical conditions are often caused by a loss
of ground, poor connection, or water intrusion into the
wiring harness.