pedal. If the display does not match the state of
the pedal, perform the proper test. If a problem
with the amber “ABS” warning indicator exists,
refer to the proper test.
6. If no other problems are found, it will be neces-
sary to road test the vehicle. THE DRBIIIt
MUST NOT BE CONNECTED TO THE
DATA LINK CONNECTOR WHEN ROAD
TESTING FOR PROPER ANTILOCK OP-
ERATION. THE SYSTEM IS DISABLED
WHILE IN DIAGNOSTIC MODE. Perform
several antilock stops from above 50 Km/h (30
mph) and then repeat steps 2, 3, and 4. If any
diagnostic trouble codes are present, proceed to
the appropriate test.
7. The following conditions should be considered
“NORMAL” operation, and no repairs should be
attempted to correct them.
– Brake pedal feedback during an ABS stop
(clicking, vibrating)
– Clicking, groaning or buzzing at 10 Km/h
(6 mph) (drive off self test)
– Groaning noise during an ABS stop
– Slight brake pedal drop and pop noise when
ignition is initially turned on
– Brake pedal ratcheting down at the end of an
ABS stop
8. If the complaint is ABS “cycling” at the end of a
stop at low speeds, it may caused by a marginal
wheel speed sensor signal. The sensor air gap,
tone wheel condition, and/or brakes hanging up
are possible causes of this condition.
9. After a road test in which no problems were
found, refer to any Technical Service Bulletins
that may apply.
5.0 REQUIRED TOOLS AND
EQUIPMENT
DRBIIIt (diagnostic read-out box)
jumper wires
ohmmeter
voltmeter
test lamp
6.0 GLOSSARY OF TERMS
ABS antilock brake system
CAB controller antilock brake
DC direct current
DLC data link connector
DRB diagnostic read–out box
EVBP electronic variable brake proportion-
ing
HCU hydraulic control unit
HZ Hertz
LF left front
LR left rear
PCI Programmable Communication
Interference
PCM Powertrain Control Module
PDC power distribution center
P/M pump motor
RF right front
RR right rear
SOL solenoid
WSS wheel speed sensor
7
GENERAL INFORMATION
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