Body Control Module (BCM)

Circuit Description

The BCM provides a ground path to the courtesy lamps on circuit 155 to S247 when commanded by the I/P Dimmer Switch input, the RH or LH Door Jamb Switch inputs, or Rear Compartment Lid Ajar Indicator Switch input. S247 distributes the ground to the following on coupe and convertible models (see Attachments 4 and 5):

Coupe

^ Dome Lamp

^ Courtesy/Reading Lamps

Convertible

^ RH/LH Rear Courtesy Lamps

^ Rear Compartment Lamp

^ Courtesy/Reading Lamps

DTC Will Set When

Circuit 156 (Courtesy Lamps Return) is shorted to B+ for greater than 50 milliseconds, while the BCM is attempting to ground this circuit. The BCM grounds circuit 156 if either door is opened or Courtesy Lamps command input is received from the I/P Dimmer Switch.

Action Taken

DTC 22 will set. No Courtesy lighting in the vehicle; I/P Dimmer Switch is inoperative. Console Compartment and I/P Compartment lamps operate normally. BCM will read out a series of flash codes upon entering Diagnostic Mode.

DTC Will Clear When

Fault is corrected and DTC memory is cleared.

DTC Chart Test Description





Numbers below refer to the steps in the diagnostic table (see Attachment 7).

1. This test checks circuit 156 for a short to B+ with the BCM disconnected.

2. Knowing that the short to B+ is in circuit 156, this test isolates the short to one side of connector C200.

4. Knowing that the short is in the C2OOC side of circuit 156, this test isolates the short to either the harness or the Rearview Mirror.

7. This test checks for a short between circuit 156 and circuit 149.

Diagnostic Aids

If the only DTC that flashes is a "History" code (DTC 32), the problem may be intermittent. Try performing the test shown while "wiggling" wiring and connectors; this can often cause the fault to appear. Check for poor connections at the BCM connector, which could cause an open or an intermittent fault. Refer to "Intermittent/History DTCs" near the beginning of this Section.