Camaro V8-5.7L VIN G (1998)
Body Control Module: Reading and Clearing Diagnostic Trouble Codes
Clearing Diagnostic Trouble Codes
Current DTCs (21 to 25) remain stored by the body control module (BCM) and are displayed in the diagnostic mode as long as the BCM detects the
fault. Once the fault is corrected, the current DTCs are cleared by the BCM. To clear history DTCs (31 to 35) press and hold the door unlock switch for
4 seconds while the BCM is in the diagnostic mode. The BCM will sound three audible warning tones to confirm that the DTCs are cleared.
To clear BCM history DTCs on vehicles without power door locks, backprobe with a fused jumper from BCM connector C1 terminal D to ground for 4
seconds. The BCM will sound three audible warning tones to confirm that the history DTCs have been cleared.
DTC Display Order
If DTC 12 and DTC 55 are displayed when the BCM is in the diagnostic mode, and no other DTCs are displayed, the BCM is operating properly.
In the diagnostic mode, diagnostic trouble codes (DTCs) are displayed in the following order:
1. DTC 12
2. Any current DTCs (DTC 21-DTC 25) or any history DTCs (DTC 31-DTC 35)
3. The remote control door lock transmitter diagnostic DTCs (DTC 41-DTC 45)
These DTCs will display if they are evoked while in the diagnostic mode.
4. The begin configuration display (DTC 55). DTC 55 and 2 configuration numbers are always displayed. The first number following DTC 55 is the
hardware configuration. The second number is the software configuration.
5. After the configuration numbers are displayed, the entire list is repeated beginning with DTC 12.
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. DTC 55 is also always displayed.
If DTC 12 and DTC 55 are displayed when the BCM is in the diagnostic mode, and no other DTCs are displayed, the BCM is operating properly.
If DTC 12 and DTC 55 are not displayed when the BCM is in the diagnostic mode, refer to DTC 12 Diagnostic System Check. See: Testing and
Inspection/Diagnostic Trouble Code Tests and Associated Procedures/Manufacturer Code Charts/DTC 12
If any other DTCs are displayed, refer to Diagnostic Trouble Code (DTC) List/type. See: Testing and Inspection/Diagnostic Trouble Code
Descriptions/Body Control Module (BCM)
System faults are stored as current or history DTCs. When working on systems controlled by the body control module, always refer to Body Control
Module and test for DTCs.
Entering Diagnostic Mode
If a malfunction occurs in a system monitored by the BCM, the BCM stores a diagnostic trouble code (DTC) in memory. DTCs are stored by the BCM
as either current or history codes. A current DTC means that the fault was present when the diagnostic mode was entered. A history DTC means the fault
occurred sometime after the DTCs were last cleared from the BCM memory. History codes are displayed even though the fault is not currently present. If
a current DTC is stored the corresponding history code will always be stored. In the diagnostic mode the BCM displays any DTCs stored in memory.
The DTCs are displayed as flash codes through the security indicator lamp on the instrument cluster (IPC). When working on any system controlled by
the BCM the technician should always refer to this section and check for DTCs.
Perform the following steps to enter the BCM diagnostic mode:
^
Turn the ignition switch to the RUN position.
^
Turn the ignition switch to the OFF position.
^
Remove the Radio fuse 17 from the I/P fuse block.
^
Turn the ignition switch to the ACCY position (the BCM sounds 1 or 2 audible warning tones).
^
Within 5 seconds, turn the ignition switch to the OFF position and immediately (within 1 second) back to the ACCY position (the BCM sounds
three audible warning tones to signal entry into the diagnostic mode).
The BCM will begin flashing trouble codes 4 seconds after entering the diagnostic mode. Each flash of the security indicator lamp on the IPC represents
a number. For example, one flash followed by two quick flashes represents code 12. Each code is displayed three times before the next code is displayed.
Stored DTCs are displayed in numerical order. Once the last code is displayed, the list begins again with the first code. The display continues until the
diagnostic mode is exited.
When in the diagnostic mode, a change at certain BCM inputs will cause the BCM to respond to the change. For example, if either door lock switch is
pressed the BCM will flash the fasten seatbelt indicator on the IPC and sound an audible warning tone. The BCM will also attempt to perform the
operation normally performed by the switch operation. In this case, as long as the system is functioning properly, the BCM will lock the doors. This is an
easy way for the technician to test the door lock actuators, switches and associated wiring without removing the door trim or components.
The BCM will also respond to a change at either shock sensor input. The tamper input is activated by minor blows to the vehicle. The shock input is
activated by heavy blows. In the diagnostic mode either will cause the BCM to activate the horn relay and the horns will sound. The BCM will also flash
