Normal Operation
WARNING: This page is about a different car, the 2006 Ford Pickup, 2006 Ford F550 Super Duty, 2006 Ford F450 Super Duty, and 2006 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
The headlamp on warning chime sounds when the parking lamps are on, the driver door is ajar, and the ignition switch is in the OFF or ACC position. When the key is inserted in the ignition lock cylinder, the key-in-ignition switch closes and sends a ground signal to the instrument cluster through circuit 158 (BK/PK). The key-in-ignition warning chime sounds if the key is in the ignition and the instrument cluster receives a driver door ajar signal.