Body Control Module (BCM)

SYSTEM DESCRIPTION
The Body Control Module (BCM) controls the interior illumination. The BCM turns ON the Interior (courtesy) lamps when one of the following actions occurs:
^ Any of the vehicle doors are opened.
^ The P dimmer switch is turned to the DOME position.
^ Exit illumination is active.
^ The doors are unlocked using the keyless entry system (BCM types 3 and 4 only).
^ The doors are unlocked using the door key cylinder (BCM type 4 only).

The BCM turns the interior (courtesy) lamps OFF when the following conditions exist:
^ All of the vehicle doors are closed.
^ The IP dimmer switch is OFF.

All the vehicle doors contain a door lock ajar switch. When the drivers door is open, the LF door lock ajar switch closes and sends a ground signal to the BCM through circuit 159.

When one of the RF, LR or RR doors is open, its corresponding door lock ajar switch closes and sends a ground signal to the BCM through circuit 49. The BCM grounds circuit 690 when detecting a ground signal in either circuits 49 or 159.

When the driver door is closed, the LF door lock ajar switch opens circuit 159.

When all of the RF, LR and RR doors are closed, the corresponding door lock ajar switches open circuit 49. The BCM then opens circuit 690 when either circuits 49 or 159 is open.

Also the BCM opens circuits 690 when the inadvertent battery power rundown protection is active, circuit 1393 is open.

DELAYED ILLUMINATION
The BCM grounds circuit 690 for 22-28 seconds when the following conditions exist. This action turns on the interior (courtesy lamps):
1. The delay illumination customization is selected (interior lighting mode 2 or 4). Refer to Body Control Module Diagnostic Information.
2. The ignition switch is in the OFF position.
3. The IP dimmer switch is OFF (circuit 156 is open).
4. When closing all the vehicle doors the BCM detects a transition from a ground signal to open circuit in either circuits 49 or 159.

The delayed illumination feature is canceled when either of the following actions occurs:
^ The ignition is turned to the ACC or RUN position.
^ The doors are locked using one of the following controls:
- A power door lock switch
- A keyless entry transmitter

EXIT ILLUMINATION
The BCM grounds circuit 690 for 22-28 seconds. The interior (courtesy) lamps turn on when the following conditions exist:
^ The exit illumination customization is selected (interior lighting mode 3 or 4). Refer to Body Control Module Diagnostic Information.
^ The ignition key is removed from the ignition key cylinder, the BCM detects a transition from ground to open in circuit 80.
^ The IP dimmer switch is OFF (circuit 156 is open).
^ All of the vehicle doors are closed at the time the ignition key is removed from the ignition key cylinder (circuits 49 and 159 are open).

The exit illumination is canceled when one of the following actions occurs:
^ The ignition switch is turned to the ACC or RUN position.
^ The doors are locked using either a power door lock switch or a keyless entry transmitter.
^ The key is inserted into the ignition cylinder a second time within 5 seconds after exit illumination starts.

INTERIOR ILLUMINATION DIM TO OFF
The BCM dims the interior (courtesy) lamps from full intensity to OFF in 3 seconds. The dimming feature starts anytime the BCM opens circuit 690. The dimming feature does not operate if any of the following actions occurs:
^ The IP dimmer switch is turned from the DOME position to the OFF position.
^ The illumination feature is cancelled by locking the doors using a power door lock switch.
^ The exit lighting feature is cancelled.

ILLUMINATION ON KEY CYLINDER UNLOCK
A BCM type 4 grounds circuit 690 for 36-44 seconds when the following conditions exist. This action turns on the interior (courtesy) lamps:
^ The ignition switch is in the OFF position.
^ Either door key cylinder lock is turned to unlock a door (grounding circuit 781).

ILLUMINATION ON REMOTE UNLOCK
The BCM types 3 and 4 grounds circuit 690 for 36-44 seconds when the following conditions exist.

This action turns on the interior (courtesy) lamps:
^ The ignition switch is in the OFF position.
^ All the vehicle doors are closed.
^ The IP dimmer switch is OFF.
^ The BCM receives a message from the Remote Control Door Lock Receiver (RCDLR) to lock or unlock the doors.

CONDITIONS FOR SETTING THE DTC
The BCM detects a short to B+ in circuit 690.

ACTION TAKEN WHEN THE DTC SETS
^ The BCM sets the Diagnostic Trouble Codes (DTCs).
^ The interior (courtesy) lamps do not illuminate.

CONDITIONS FOR CLEARING THE DTC
^ A short to B+ in circuit 690 is no longer present between the BCM and any of the courtesy lamps.
^ After the repairs are completed, refer to Body Control Module Diagnostic Information

DIAGNOSTIC AIDS
^ Inspect for a short to B+ in circuit 690.
^ Move the wiring and the connectors while you complete the test. This will cause the malfunction to appear.

INTERIOR LIGHTING MODES
Complete the following steps in order to change the interior lighting mode:
1. Turn the IP dimmer switch OFF.
2. Turn the ignition switch to the OFF position.
3. Remove the MALL PGM fuse.
4. Turn the ignition switch to the ACC position.

The BCM sounds the chime a number of times equivalent to the BCM type installed on the vehicle. At this time the BCM has entered the feature customization mode. In order to change the interior lighting, cycle the IP dimmer switch from OFF to DOME back to OFF. The BCM sounds a chime a number of times equivalent to the lighting mode. There are four lighting modes:
^ Mode 1
Exit illumination and delayed illumination are disabled.
^ Mode 2
Delay illumination is enabled.
^ Mode 3
Exit illumination is enabled.
^ Mode 4
Exit illumination and delayed illumination are enabled.

BCM INPUT/OUTPUT TEST PROCEDURE
1. Turn the IP dimmer switch OFF.
2. Turn the ignition switch to the OFF position.
3. Remove the MALL PGM fuse.
4. Turn the ignition switch to the ACC position. The BCM sounds the chime a number of times equivalent to the BCM type installed on the vehicle.
5. Within 1 second, turn the ignition switch from the ACC position to the OFF position then back to the ACC position.
The BCM sounds any DTCs that are stored.
6. Turn the IP dimmer switch to the DOME position. The BCM enters the Input/Output test. There are 7 steps in the Input/Output test:
^ Test 1 de-energizes circuit 1393 (protected courtesy lamp output).
^ Test 2 energizes circuit 1393.
^ Test 3 grounds circuit 690 (courtesy lamps control).
^ Test 4 energizes the theft deterrent relay for 1 second by grounding circuit 352 and turns on the headlamps (BCM type 4 only).
^ Test 5 energizes the horn relay for 25 ms by grounding circuit 28 and sounds the horn (BCM type 4 only).
^ Test 6 turns on the theft deterrent indicator lamp by grounding circuit 749 (BCM type 4 only).
^ Test 7 turns off the theft deterrent indicator lamp by opening circuit 749 (BCM type 4 only).

The BCM completes the steps of the Input/Output test in numerical order.

In order to move to the next test, cycle the IP dimmer switch from DOME to OFF then back to DOME. The BCM will sound the chime a number of times equivalent to the Input/Output test number above. The Input/Output test sequence repeats until the ignition switch is turned to the OFF position.

Diagnostic Chart:

TEST DESCRIPTION
The number(s) below refer to the step number(s) on the diagnostic table.
1. Always perform the BCM diagnostic system check before attempting to diagnose this DTC.
2. This step checks if the BCM is able to control the courtesy lights circuit 690.
3. This step checks for a short to B+ in circuit 690.