Operation CHARM: Car repair manuals for everyone.

Lights On Warning

The lamps-on chime activates with the headlamp switch in HEAD or PARK position, the left front door open, and the ignition switch in OFF or ACC. When the headlamp switch is in HEAD or PARK, switch contacts close in order to provide a ground input on the corresponding circuit to the BCM, which turns on the lamps. Opening the left front door closes the left front door jamb switch. The left front door sends a message to the BCM on the class 2 serial data line, signalling that the door is open. If the conditions to activate the chime are met, the BCM sends a message on the class 2 serial data line requesting the radio to activate the lamps-on chime.