1988 JEEP CHEROKEE brake sensor

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

* CARTRIDGE ERROR
* HIGH BATTERY
* KEYPAD TEST FAILURE
* LOW BATTERY
* RAM TEST FAILURE
3) If no error messages appear, display will read as follows
after a few seconds: 1) VEHICLES TESTED, 2) HOW TO USE, 3) CONFIGURE
and 4) SELECT SYSTEM.
4) Select 4) SELECT SYSTEM to enter diagnostic system. Once
in SELECT SYSTEM, select 2) TRANSMISSION to enter transmission.
Display will read 1) EATX and 2) AW4.
5) Select 2) AW4. After a few seconds display will change to
read AW4, VERSION 01. After a few seconds, display will read AW4 MENU,
1) SYSTEM TEST and 2) READ FAULTS. If DOWN ARROW is depressed 3 times,\
display will read as follows: 3) STATE DISPLAY, 4) ACTUATOR TESTS and
5) ADJUSTMENTS.
NOTE: The ACTUATOR TESTS and ADJUSTMENTS cannot be used when
diagnosing the AW-4 transmission.
Retrieving Diagnostic Trouble Codes
1) Select 2) READ FAULTS from AW4 MENU. If no diagnostic
trouble code exists, display will read as follows: AW4 FAULTS, NO
FAULTS DETECTED.
2) If diagnostic trouble code exists, the following message
will be displayed: 1 OF 3 FAULTS. This number will vary depending on
number of diagnostic trouble codes stored in the TCM memory.
3) Diagnostic trouble code and message will be displayed.
Press DOWN ARROW key to display next diagnostic trouble code. To
identify diagnostic trouble code, see DIAGNOSTIC TROUBLE CODE
IDENTIFICATION table.
NOTE: See TROUBLE SHOOTING CHARTS to diagnose faults indicated by
trouble codes.
NOTE: Valve body solenoid diagnostic trouble code 700 may appear
in a FAULT PRESENT or FAULT STORED status. Status will be
displayed along with diagnostic trouble code. Diagnostic
trouble code must be diagnosed depending on the status. See
TEST 1A - VERIFICATION OF THE COMPLAINT under TROUBLE
SHOOTING CHARTS.
DIAGNOSTIC TROUBLE CODE IDENTIFICATION









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Trouble Code Problem Area
700 ( 1) .............................. Valve Body Solenoid
702 ......................................... Speed Sensor
703 ............................... ( 2) Gear Select Switch
705 ............................. Throttle Position Sensor
706 ......................................... Brake Switch
707 ..................................... Wrong TCM Or TCU
( 1) - Trouble code may apply to individual valve body
solenoids. Valve body solenoid may be referred to
as S1 for No. 1, S2 for No. 2 and S3 for No. 3.
( 2) - Gear select switch is the same as the neutral
safety switch.









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CLEARING DIAGNOSTIC TROUBLE CODES

1) Once all diagnostic trouble codes have been obtained,
diagnostic trouble code(s) can be erased from TCM memory by
disconnecting electrical connector from TCM for at least 15 seconds.
CAUTION: DO NOT disconnect battery, as data stored in other vehicle
control modules will be lost.
2) The TCM is located behind right side of instrument panel
on Cherokee. See Fig. 1.
DRB-II OPERATING MODES
NOTE: The DRB-II can be operated in several different modes to
perform various tests. Except for voltmeter/ohmmeter and HOW
TO USE modes, all other operating modes are selected from
AW4 MENU. See ENTERING AW4 MENU under RETRIEVING DIAGNOSTIC
TROUBLE CODES.
VOLTMETER/OHMMETER MODE
To access voltmeter/ohmmeter mode, connect Red volt-ohmmeter
test lead to Red port at top right corner of DRB-II. There are 2
different ports on top of DRB-II; ensure test lead is connected to
proper port. Access voltmeter or ohmmeter mode using manufacturer's
instructions.
NOTE: The DRB-II is grounded through transmission diagnostic
connector and only one test lead is required. When
diagnosing transmission, an external volt-ohmmeter may
sometimes be required.
HOW TO USE MODE
1) This mode gives instructions on DRB-II usage. To enter
this mode, see steps 1) through 4) of ENTERING AW4 MENU under
RETRIEVING DIAGNOSTIC TROUBLE CODES . Select 2) HOW TO USE.
2) A series of screens will be displayed explaining DRB-II
key usage for system diagnosing.
SYSTEM TEST MODE
NOTE: SYSTEM TEST mode consists of a stationary test and a road
test. The SYSTEM TEST mode must be selected from AW4 MENU.
See ENTERING AW4 MENU under RETRIEVING DIAGNOSTIC TROUBLE
CODES.
1) Stationary test monitors transmission system data, current
valve body solenoid failures, switch failures, correct TCM
application, calibration and operation. Road test checks all valve
body solenoids and speed sensor.
2) Technician will be instructed to place shift lever in each
gear position, starting by shifting into 1-2 position. Once
transmission is in Park, brake pedal must be depressed to check brake
switch.
3) After brake switch is checked, technician will be
instructed to slowly depress throttle. DRB-II will display 7 asterisks
( ******* ) corresponding to throttle position. While depressing
accelerator, Throttle Position Sensor (TPS) sweeps through entire
range of positions required by the TCM.
4) A corresponding asterisk will be cleared from DRB-II
display as each throttle position is sensed by TCM. Several attempts
may be required to clear all asterisks from the display, depending on

how fast accelerator is depressed.
5) After throttle position is checked, technician will be
instructed to drive the vehicle. The DRB-II will indicate if a
requested action is seen by the TCM. If technician is requested to
perform a particular operation and TCM does not acknowledge the
action, press ENTER key to continue testing.
6) The TCM will instruct technician to accelerate vehicle at
light throttle to ensure transmission shifts through all gears,
indicating proper valve body solenoid operation.
7) During road test, ensure vehicle can be accelerated slowly
and evenly to allow transmission to enter all gear ranges without
downshifting or braking. If a failure is sensed, a diagnostic trouble
code will be displayed on DRB-II.
NOTE: If TCM senses a failure, control logic activates a specified
valve body solenoid to obtain a certain gear depending on
failure. Because transmission diagnostic trouble codes are
displayed one at a time, multiple diagnostic trouble codes
must be identified by retesting transmission.
STATE DISPLAY MODE
NOTE: STATE DISPLAY mode must be selected from AW4 MENU. See
ENTERING AW4 MENU under RETRIEVING DIAGNOSTIC TROUBLE CODES .
Select 3) STATE DISPLAY on DRB-II.
Module Information
When selecting module information option, the TCM version
will be indicated by a 2-digit number. Information can be used to
verify proper TCM application.
Sensor
1) When selecting sensor option, TPS and RPM indications will
be shown. The TPS indicator will display a 7 segment bar graph,
indicating TPS position and throttle plate angle.
2) A properly operating TPS should indicate 7 segments
through full throttle travel. The RPM indicator will display
transmission output shaft revolutions per minute.
Brake Switch Or Input/Output
Display indicates brake switch status, indicating whether
brake pedal is applied or released. Display also indicates shift lever
position, whether a valve body solenoid is on or off and present
transmission operating gear.
DRB-II PROBLEMS & ERROR MESSAGES
CARTRIDGE ERROR
1) If CARTRIDGE ERROR 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 CARTRIDGE ERROR message is displayed, replace DRB-II
cartridge and proceed with diagnostics. If KEYPAD TEST FAILURE message
is displayed, replace DRB-II and proceed with diagnostics.
HIGH BATTERY
If HIGH 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

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

SHOE HARDWARE
SHOES
SOCKETS
SPEED SENSORS (ELECTRONIC WHEEL AND VEHICLE)
STEEL BRAKE LINES
STOPLIGHT SWITCHES
SWITCHES
TIRES
TOOTHED RINGS (TONE WHEEL)
VACUUM BOOSTERS
VACUUM HOSES
VALVES
WHEEL ATTACHING HARDWARE
WHEEL BEARINGS, RACES AND SEALS
WHEEL CYLINDERS
WIRING HARNESSES
INTRODUCTION TO MOTORIST ASSURANCE PROGRAM (MAP)
OVERVIEW OF MOTORIST ASSURANCE PROGRAM
The Motorist Assurance Program is the consumer outreach
effort of the Automotive Maintenance and Repair Association, Inc.
(AMRA). Participation in the Motorist Assurance Program is drawn from
retailers, suppliers, independent repair facilities, vehicle
manufacturers and industry associations.
Our organization's mission is to strengthen the relationship
between the consumer and the auto repair industry. We produce
materials that give motorists the information and encouragement to
take greater responsibility for their vehicles-through proper,
manufacturer-recommended, maintenance. We encourage participating
service and repair shops (including franchisees and dealers) to adopt:\
1) a Pledge of Assurance to their Customers and
2) the Motorist Assurance Program Standards of Service.
All participating service providers have agreed to subscribe
to this Pledge and to adhere to the promulgated Standards of Service
demonstrating to their customers that they are serious about customer
satisfaction.
These Standards of Service require that an inspection of the
vehicle's (problem) system be made and the results communicated to the\
customer according to industry standards. Given that the industry did
not have such standards, the Motorist Assurance Program successfully
promulgated industry inspection communication standards in 1994-95 for
the following systems: Exhaust, Brakes, ABS, Steering and Suspension,
Engine Maintenance and Performance, HVAC, and Electrical Systems.
Further, revisions to all of these inspection communication standards
are continually re-published. In addition to these, standards for
Drive Train and Transmissions have recently been promulgated.
Participating shops utilize these Uniform Inspection & Communication
Standards as part of the inspection process and for communicating
their findings to their customers.
The Motorist Assurance Program continues to work
cooperatively and proactively with government agencies and consumer
groups toward solutions that both benefit the customer and are
mutually acceptable to both regulators and industry. We maintain the
belief that industry must retain control over how we conduct our
business, and we must be viewed as part of the solution and not part
of the problem. Meetings with state and other government officials
(and their representatives), concerned with auto repair and/or
consumer protection, are conducted. Feedback from these sessions is
brought back to the association, and the program adjusted as needed.
To assure auto repair customers recourse if they were not

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.