Table of Contents
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1.0 INTRODUCTION
The procedures contained in this manual include
all the specifications, instructions, and graphics
needed to diagnose the 2003 TJ Chassis system
problems: Teves Mark 20i Antilock Braking System
(ABS) and Axle Lock. The diagnostics in this man-
ual are based on the failure condition or symptom
being present at time of diagnosis.
Follow the recommendations below when choos-
ing your diagnostic path.
1. First make sure the DRBIII is communicating
with the CAB. If the DRBIII
Response'' condition, you must diagnose that
first.
2. Read DTC's (diagnostic trouble codes) with the
DRBIII .
3. If no DTC's are present, identify the customer
complaint.
4. Once the DTC or customer complaint is identi-
fied, locate the matching test in the Table of
Contents and begin to diagnose the symptom.
All component location views are in Section 8.0.
All connector pinouts are in Section 9.0. All sche-
matics are in Section 10.0.
An asterisk (*) placed before the symptom de-
scription indicates a customer complaint.
When repairs are required, refer to the appropri-
ate service manual for the proper removal and
repair procedure.Diagnostic procedures change every
year. New diagnostic systems may be added; carryover
systems may be enhanced. READ THIS MANUAL
BEFORE TRYING TO DIAGNOSE A VEHICLE DI-
AGNOSTIC TROUBLE CODE. It is recommended
that you review the entire manual to become familiar
with all new and changed diagnostic procedures.
After using this book, if you have any comments
or recommendations, please fill out the form at the
back of the book and mail it back to us.
1.1 SYSTEM COVERAGE
This diagnostic manual covers the Teves Mark
20i Antilock Braking System (ABS) found on the
Jeep Wrangler. Diagnosis of the Axle Lock is cov-
ered in this manual.
1.2 SIX-STEP TROUBLESHOOTING
PROCEDURE
Diagnosis of the antilock brake system is done in
six basic steps:
•
verification of complaint
•
verification of any related symptoms
•
symptom analysis
•
problem isolation
•
repair of isolated problem
•
verification of proper operation
2.0 IDENTIFICATION OF
Vehicles equipped with the Teves Mark 20i an-
tilock brake system can be identified by the pres-
ence of the hydraulic control unit (HCU) located
under the hood near the power brake booster. Vehi-
cles equipped with Axle Lock can be identified by
the presence of the Axle Lock Switch located on the
displays a ''No
lower center of the instrument panel.
3.0 SYSTEM DESCRIPTION AND
3.1 TEVES MARK 20I SYSTEM
An electronic control module is used to monitor
wheel speeds and to modulate (control) hydraulic
pressure in each brake channel to prevent wheel
lock-up during braking.
During a non-ABS stop, the system functions as a
standard front/rear split configuration. The pri-
mary hydraulic system supplies brake fluid pres-
sure to the front brakes, and the secondary hydrau-
lic system supplies the rear brakes. A conventional
combination/proportioning valve is used.
During an ABS stop, the system still uses the
front/rear hydraulic split; however, the brakes sys-
tem pressure is further split into three control
channels. During ABS operation, the front wheels
are controlled independently and are on two sepa-
rate control channels. The rear wheels are con-
trolled together through one control channel. By
using a separate control channel for each front
wheel, more steering control is maintained during
maximum braking.
During an antilock stop, ''wheel lock-up'' does not
necessarily mean that the wheel has locked, it
means only that the wheel is turning slower than
the vehicle speed. This is called ''wheel slip'' and is
indicated as a percentage. 0% slip means that the
wheel is rolling free and 100% slip means that the
wheel is locked. The antilock system maintains an
average of approximately 20% wheel slip.
It is important to remember that the antilock
brake system does not shorten the vehicle stopping
distance under all driving conditions, but provides
improved control of the vehicle while stopping.
Vehicle stopping distance is still dependent on ve-
hicle speed, weight, tires, road surface, and other
factors.
1
GENERAL INFORMATION
SYSTEM
FUNCTIONAL OPERATION
DESCRIPTION
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