Circuit Operation

Battery voltage is applied to the Headlamp bulbs at all times. The Headlamps are controlled by supplying ground for the lamps through the Turn/Headlamp Switch Assembly or the Body Function Controller (BFC). With the Turn/Headlamp Switch in the ON position, ground is supplied through circuit 150.

The Daytime Running Lamps (DRL) are controlled by the BFC. The system operates by allowing the headlamps to operate at a reduced intensity when the vehicle is operating (the engine is running and transaxle is not in PARK) and the normal headlamps are not on. The BFC turns the system on by grounding circuit 592, thereby energizing the DRL Relay. This will allow a reduced voltage to flow across the headlamps by use of the DRL Resistor. When the Headlamp Switch is turned ON, there is normal headlamp operation.

The BFC also has an input from the Park Brake. If the Park Brake is in the ON position, the Daytime Running Lamps will remain disabled until the Park Brake is put in the OFF position.

The BFC also has an input from the Fog Lamp Switch. The BFC enables the Fog Lamp Relay when it receives an ON request input from the Fog Lamp Switch. The Ignition Switch must also be in the RUN position with the Headlamp Switch in PARK or HEAD. If the Headlamp Switch is in the HEAD position, the High/Low Beam Switch must be in the LOW position for the Fog Lamp Relay to be enabled by the BFC.

The BFC also controls the Head lamps and Park Lamps by energizing the Automatic Lamp Control Relay. The BFC uses an Ambient Light Sensor to determine available light levels, and when to energize the Automatic Lamp Control Relay. The BFC also energizes the Park Lamp Relay to turn on the exterior lamps. Refer to Exterior Lights, for further information. Testing and Inspection