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BODY CONTROL MODULE (Continued)
When replacing a BCM there are three modules
available:
• Base
• Midline
• Highline
The Midline controller is used on vehicles that
have Power Door Locks and the Highline controller is
used for vehicles equipped with a Power Liftgate. If a
vehicle is equipped with the Vehicle Theft Security
System, the Midline/Highline controller becomes a
Premium when the theft feature is enabled.
CAUTION: Do not swap Body Control Modules
between vehicles or body controller's off the shelf.
The BCM has internal diagnostic capability that
assists in diagnosing the system error. When an
OPEN or a SHORT circuit exists, the diagnostic tool
can be used to read the BCM faults. The faults are
very descriptive in identifying the appropriate fea-
ture that has faulted.
The only two faults that the BCM logs that con-
clude the replacement of a BCM are faults;
• # 01 - Internal BCM failure (replace BCM)
• # 1F - J1850 Internal Hardware Failure (replace
BCM)
Otherwise the appropriate diagnostic procedures
for each of the features should be taken when the
BCM logs a fault.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the lower instrument panel silencer.
(3) Remove the knee blocker and reinforcement
(Refer to 23 - BODY/INSTRUMENT PANEL/KNEE
BLOCKER REINFORCEMENT - REMOVAL).
(4) Disconnect the five wire connectors from the
bottom of the Body Control Module (BCM).
(5) Move bulkhead wiring aside.
(6) Remove the screws holding the BCM to the
bulkhead.
(7) Remove the BCM from the mounting bracket.
INSTALLATION
(1) Install the BCM to the mounting bracket.
(2) Install the screws holding the BCM to the
bulkhead.
(3) Connect the five wire connectors to the bottom
of the Body Control Module (BCM).
(4) Install the knee blocker and reinforcement
(Refer to 23 - BODY/INSTRUMENT PANEL/KNEE
BLOCKER REINFORCEMENT - INSTALLATION).
(5) Install the lower instrument panel silencer.
(6) Connect the battery negative cable.
(7) Verify proper operation of BCM and its func-
tions.
ELECTRONIC CONTROL MODULES
CONTROLLER ANTILOCK
BRAKE
DESCRIPTION
The controller antilock brake (CAB) is a micropro-
cessor-based device which monitors the antilock
brake system (ABS) during normal braking and con-
trols it when the vehicle is in an ABS stop. The CAB
is mounted to the HCU as part of the integrated con-
trol unit (ICU) (Fig. 2). The CAB uses a 24-way elec-
trical connector on the vehicle wiring harness. The
power source for the CAB is through the ignition
switch in the RUN or ON position. The CAB is on
the PCI bus.
Fig. 2 Integrated Control Unit (ICU)
1 - PUMP/MOTOR
2 - HCU
3 - PUMP/MOTOR CONNECTOR
4 - CAB
OPERATION
The primary functions of the controller antilock
brake (CAB) are to:
• Monitor the antilock brake system for proper
operation.
• Detect wheel locking or wheel slipping tenden-
cies by monitoring the speed of all four wheels of the
vehicle.
• Control fluid modulation to the wheel brakes
while the system is in an ABS mode.
• Store diagnostic information.
• Provide communication to the DRBIII scan tool
while in diagnostic mode.
• Illuminate the amber ABS warning indicator
lamp.
• (With traction control only) Illuminate the TRAC
ON lamp in the message center on the instrument
panel when a traction control event occurs.
8E - 5
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