Circuit Description

WARNING: This page is about a different car, the 2002 Pontiac Grand Prix. However, it is still accessible from the selected car via links, so may be relevant.

The body control module (BCM) controls the interior illumination. The BCM turns on the interior (courtesy) lamps when the following actions occur:

Any of the vehicle doors are opened.
The instrument panel dimmer switch is turned to the DOME position.
Exit illumination is active.
The doors are unlocked through the keyless entry system (BCM type 3 and type 4 only).
The doors are unlocked using the door key cylinder (BCM type 3 and type 4 only).

The BCM turns the interior lamps off when all the vehicle doors are closed and the instrument panel dimmer switch is in the OFF position.

All the vehicle doors contain a door lock ajar switch. When the driver door is open, the left front door lock ajar switch closes and sends a ground signal to the BCM through the driver door ajar input circuit.

When one of the right front, left rear, or right rear doors is open, its corresponding door lock ajar switch closes and sends a ground signal to the BCM through the corresponding door ajar input circuit. The BCM grounds the courtesy lights control output circuit when detecting a ground signal in any of the following circuits:

Driver door ajar input circuit
Passenger door ajar input circuit

When the driver door is closed, the left front door lock ajar switch opens the driver door ajar input circuit. When all of the right front, left rear, and right rear doors are closed, their corresponding door lock ajar switches opens the corresponding door ajar input circuit. The BCM then opens courtesy lamp low control circuit when any one of the door ajar input circuits is open.

The BCM powers the interior lights through the protected battery positive voltage courtesy lamps supply circuit. The BCM controls the power supplied to the protected battery positive voltage courtesy lamp supply circuit for inadvertent load (battery rundown) protection. The BCM also opens the courtesy lamps supply voltage circuit when the inadvertent battery power rundown protection is active.