GM Service Manual Online
For 1990-2009 cars only

Using a feature called inadvertent power control, the body control module (BCM) supplies power to all of the following lamps through CKT 1732:

    • The courtesy lamps
    • The dome lamp
    • The rearview mirror reading lamps (if equipped)
    • The rear compartment lamp
    • The instrument panel compartment lamp

The right front door jamb switch turns on the interior lamps through the BCM by grounding CKT 395. When the right front door is open, the switch is closed. This condition provides a ground and a door open input to the BCM. The BCM then grounds the following lamps through CKT 156 in order to turn the lamps on:

    • The courtesy lamps
    • The dome lamp
    • The rearview mirror reading lamps (if equipped)

The left front door jamb switch and the rear door jamb switches turn on the interior lamps by grounding CKT 394 to the BCM. When the ignition key is removed from the lock cylinder, the interior lamps remain on for approximately 10 seconds then slowly fade out.

The BCM provides an interior lamps-on delay after a door is opened. The lamps remain on for approximately 10 seconds or until the ignition switch is turned to the ON position then fade out.

The rearview mirror reading lamps are controlled by the following actions:

    • The rearview mirror reading lamps switches can override the BCM by grounding the lamps through CKT 150.
    • Opening any door with the switch in the OFF position will light the lamps.
    • Moving the dimmer switch to the dome lamp position with the switches in the OFF position will light the lamps.

When a door unlock signal or a trunk release signal from the remote keyless entry keyfob is received by the omron module, the BCM turns on the interior lamps. Voltage is applied at all times through the RDO/INT LP fuse to the BCM. The BCM applies voltage at all times to the inadvertent power control relay, internal to the BCM.

Battery Run Down Protection

When the ignition switch is in the OFF position, the BCM turns off the power to all of the interior lamps after 18-22 minutes.

The BCM will reset the inadvertent power control relay output when one of the following actions is performed:

    • Open or close a door.
    • Turn the ignition switch to the ON position.
    • Turn off any interior lamps that may be on.
    • Press the power door lock switch/keyfob button.
    • Press the decklid release keyfob button.