1988 JEEP CHEROKEE ECO mode

be obtained. During high speeds "on" time may be 10 percent and "off"
time 90 percent. During low speeds with high electrical loads, "on"
time may be 90 percent and "off" time 10 percent.
SI SERIES
A rectifier bridge, connected to stator windings, contains 6
diodes (3 positive and 3 negative) molded into an assembly. This
rectifier bridge changes stator AC voltage into DC voltage, which
appears at output terminal.
Alternator field current is supplied through a diode trio
which is also connected to stator windings. A capacitor is mounted to
end frame, protecting rectifier bridge and diodes from high voltage
and suppressing radio interference noise.
TROUBLE SHOOTING
NOTE: See the TROUBLE SHOOTING - BASIC PROCEDURES article
in the GENERAL TROUBLE SHOOTING section.
TESTING
PRELIMINARY INFORMATION
NOTE: Before making electrical checks, visually inspect all
terminals for clean, tight connections. Check alternator
mounting bolts and drive belt tension. Battery must be in
good condition to test charging system.
TESTING (ON-VEHICLE)
CS SERIES
Over/Undercharged Battery (W/ STandard Instruments)
1) If an overcharging condition is suspected, run engine at a
moderate speed. Connect a voltmeter across battery terminals. If
voltmeter indicates more than 16 volts, replace alternator.
2) If an undercharging condition is suspected, disconnect
2
wire connector from alternator. Turn ignition on with engine off.
Connect a voltmeter between terminal "L" in wiring harness and ground.
Record reading.
3) If terminal "I" is used, connect voltmeter between
terminal "I" and ground. Record reading. If voltmeter reads battery
voltage, circuits are okay. If voltmeter reads zero, this indicates an
open circuit between terminal checked and battery. Repair as
necessary.
Overcharged Battery (W/ Gauges)
If an overcharging condition is suspected, run engine at a
moderate speed. Connect a voltmeter across battery terminals. If
voltmeter indicates more than 16 volts, replace alternator.
Alternator Output Test (W/ Standard Instruments Or Gauges)
1) Run engine at moderate speed, all electrical accessories
off. Measure voltage across battery, if above 16 volts, replace
alternator.
2) Connect an ammeter in circuit at "BAT" terminal of
alternator. Turn on all available accessories. Connect a battery load
tester across battery. Operate engine at 2000 RPM and adjust battery
load tester as required to obtain maximum current output while

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AN TI- L O CK B RAK E S A FE TY P R EC AU TIO NS

1988 J e ep C hero ke e
GENERAL INFORMATION
Anti-Lock Brake Safety Precautions
* PLEASE READ THIS FIRST *
This article is intended for general information purposes
only. This information may not apply to all makes and models. If
vehicle is equipped with Anti-Lock Brake System (ABS), refer to
appropriate ANTI-LOCK BRAKE SYSTEM article in the BRAKES section for
description, operation, depressurizing, testing, system bleeding,
trouble shooting and servicing of specific system.
WARNING: Failure to depressurize ABS could lead to physical injury.
ANTI-LOCK BRAKE SAFETY PRECAUTIONS
WARNING: Failure to depressurize ABS could lead to physical injury.
* NEVER open a bleeder valve or loosen a hydraulic line
while ABS is pressurized.
* NEVER disconnect or reconnect any electrical connectors
while ignition is on. Damage to ABS control unit may result.
* DO NOT attempt to bleed hyudarulic system without first
referring to the appropriate ANTI-LOCK BRAKE SYSTEM article
in the BRAKES section.
* Only use specially designed brake hoses/lines on ABS equipped
vehicles.
* DO NOT tap on speed sensor components (sensor, sensor rings).
Sensor rings must be pressed into hubs, NOT hammered into
hubs. Striking these components can cause demagnetization or
a loss of polarization, affecting the accuracy of the speed
signal returning to the ABS control unit.
* DO NOT mix tire sizes. Increasing the width, as long as tires
remain close to the original diameter, is acceptable. Rolling
diameter must be identical for all 4 tires. Some
manufacturers recommend tires of the same brand, style and
type. Failure to follow this precaution may cause inaccurate
wheel speed readings.
* DO NOT contaminate speed sensor components with grease. Only
use recommended coating, when system calls for an
anti-corrosion coating.
* When speed sensor components have been removed, ALWAYS check
sensor-to-ring air gaps when applicable. These specifications
can be found in each appropriate article.
* ONLY use rocommended brake fluids. DO NOT use silicone brake
fluids in an ABS equipped vehicle.
* When instlling transmittion devices (CB's, telephones, etc.)
on ABS equipped vehicles, DO NOT locate the antenna near the
ABS control unit (or any control unit).
* Disconnect all on-board computers, when using electric
welding equipment.
* DO NOT expose the ABS control unit to prolonged periods of
high heat (185
F/85C for 2 hours is generally considered a
maximum limit).

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

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

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.
(1) - Inoperative includes intermittent operation or out of OEM
specification.
( 2) - Determine cause and correct prior to repair or
replacement of part.









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ROTORS
Determine the need to recondition based upon individual rotor
conditions that follow. Friction material replacement does not require
rotor reconditioning unless other justifications exist. DO NOT
recondition new rotors unless they are being pressed or bolted onto an
existing hub. It is not necessary to replace rotors in axle sets.
However, when replacing or reconditioning a rotor due to the
conditions that follow, you may suggest reconditioning of the other
rotor on the same axle to eliminate uneven braking behavior.
Determine the need to replace based upon the individual rotor
conditions that follow. Reconditioning is defined as machining and
block sanding, or block sanding only. Block sanding is defined as
using 120-150 grit sandpaper with moderate to heavy force for 60
seconds per side. Always wash rotors after servicing or before
installing.
ROTOR INSPECTION









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Condition Code Procedure
Corrosion affecting
structural integrity ... A ........ ( 1) Require replacement.
Cracked ................. B ............ Require replacement.
Hard spots .............. 2 ....... Suggest reconditioning or
replacement of rotor according
to OEM specifications.
Lateral runout (wobble)
exceeds OEM
specifications ......... B ............ Require re-indexing,
reconditioning, or replacement
according to specifications.
Measured thickness is less
than OEM discard
specifications ......... B ............ Require replacement.
Rotor thickness is less
than OEM "machine to"
specifications but thicker
than "discard at"
specifications, and the
rotor does not require
reconditioning ......... 1 ........ ( 2) Suggest replacement.
Rotor thickness will be
less than OEM "machine to"
specifications after
required

guide, adjuster screw assembly, parking brake lever and lever pivot
pin with molybdenum disulphide grease.
2) Connect parking brake lever to secondary brake shoe with
washer and "U" clip. Crimp ends of clip to secure clip on pivot.
Remove wheel cylinder clamp. Position brake shoes on brake support
plate and install hold-down springs.
3) Install parking brake lever strut and spring. Install
adjuster cable guide plate and adjuster cable on anchor pin. Install
primary return spring. Install guide to secondary brake shoe. Install
secondary return spring.
4) Install adjuster screw, spring and lever. Connect lever to
cable. Using Brake Gauge (J-21177-01), preset brake shoe adjustment.
Install brake drums. Adjust brake shoes with drum in place.
5) Install wheels and lower vehicle. To adjust and balance
brake system, apply and release brakes 10-15 times while driving
forward and backward. Road test vehicle.
DRUM BRAKE SHOES - GRAND WAGONEER
Removal
1) Raise vehicle and support with safety stands. Remove
wheels. On models with full-floating rear axle, remove 2 screws that
retain drum on hub.
2) On all models, remove primary shoe return spring,
automatic adjuster actuator spring and secondary shoe return spring.
Remove hold-down springs. Remove brake shoe assemblies. See Fig. 10.
3) Disengage parking brake cable from parking brake lever.
Remove parking brake strut and brake shoe assembly as a unit. Place
wheel cylinder clamps over cylinders in order to retain pistons.
4) Inspect automatic adjuster lever and pivot, actuating
lever, parking brake lever, automatic adjuster and springs. Replace
weak springs, bent levers and parts that are worn or broken.
Fig. 10: Exploded View of Drum Brake Assembly (Grand Wagoneer)
Courtesy of American Motors/Jeep Corp.
Installation
1) Clean support plate. Apply a thin film of molybdenum

which has not pitted or roughened surface of cylinder can be removed
with crocus cloth. If cylinder bore is scored, pitted or corroded,
replace master cylinder.
Reassembly
1) Install replacement tube seats by threading a spare brake
line tube nut into hole. Turn nut in until tube seat bottoms. Do not
cock tube seat in hole. Remove nut and check for burrs which may have
been loosened by nut. Install secondary seals on secondary piston,
with cup lips facing away from each other.
2) Install primary seal, spring retainer and return spring on
secondary piston. Install seal so lip faces interior of master
cylinder when installed. Lubricate cylinder bore with clean brake
fluid and install secondary piston assembly. Lubricate primary piston
seals and install primary piston assembly in bore. Hold primary piston
downward in bore and install snap ring.
3) Install composite reservoir (if equipped). On models with\
push-on composite fluid reservoir, invert reservoir, install grommets
and press on body using a rocking motion. Install master cylinder
cover and new diaphragm.
4) On vehicles with manual brakes, assemble brake pedal push
rod through retainer (if equipped). Push retainer over end of master
cylinder and install rubber boot.
Fig. 15: Exploded View of Master Cylinder (Grand Wagoneer)
Courtesy of American Motors/Jeep Corp.
WHEEL CYLINDER