GMC Chevrolet Camaro 1998 Service Manual page 686

a . .
444 Body Control System
DTC 12 Diagnostic System Check
Circuit Description
Voltage is applied at all times from the POWER ACCY
Fuse 7 through circuit 640 to the SECURITY indicator
lamp on the instrument cluster.
Ground is applied by the body control module (BCM)
through circuit 728 to the SECURITY indicator
lamp when the ignition switch is in the RUN or BULB
TEST position.
When the ignition switch is turned to the RUN or
BULB TEST position, the SECURITY indicator lamp
illuminates for approximately 5 seconds in order
to verify the circuit operation.
The BCM also uses the SECURITY indicator lamp in
order to display the DTC flash codes by grounding
CKT728.
Conditions for Setting the DTC
DTC 12 is always set and displayed when the body
control module (BCM) is in the diagnostic mode.
DTC 12 indicates that the diagnostic function is in
progress. If DTC 12 does not display when the BCM is
in the diagnostic mode, refer to the following
diagnostic chart.
Body and Accessories
Test Description
The numbers below refer to the step numbers on 1he
diagnostic table.
1. This step tests the SECURITY indicator lamp
operation at the BULB TEST.
2. This step tests the BCM operation in the
diagnostic mode.
3. This step tests the BCM output to the retained
accessory power (RAP) components.
4. This step tests circuit 75 for a short to ground.
5. This step tests the BCM operation in the
diagnostic mode after the repair to circuit 75.
7. If the SECURITY indicator lamp does not
illuminate, this step determines if the fault is in the
BCM or the SECURITY indicator circuit.
8. This step tests for a poor connection at the BCM.
9. This step tests for an open in circuit 640.
10. This step tests for an open in circuit 728.
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