Low Beam System Operation

The headlamps may be turned on two different ways. First, when the end of the of the turn signal/headlamp switch lever is turned to the second detent position, the headlamps will illuminate. A ground signal is provided to the DRL control module. The module then provides a ground path to the coils of the head relay and DRL relay. Since the head relay is provided with battery voltage to both the contacts and the coil, the coil becomes energized and closes the contacts providing voltage to the dimmer relay, through the DRL fuse to the DRL relay and through both head fuses (LH-LWR and RH-LWR) to both LH and RH low beam lamps. With voltage and ground provided to the coil of the DRL relay, the coil becomes energized and closes the contacts providing a direct path to ground for both headlamps through SP254 to G103. With voltage and ground provided, the low beam lamps light. Second, with the switch in the OFF position, for Automatic Lamp Control (ALC). During ALC the headlamps will be in one of the following modes of operation:
^ Daytime Running Lamp (DRL) operation in daylight conditions, refer to Daytime Running Lamps (DRL) below for the operation of the circuit.
^ Low beam headlamp operation in low light conditions. When the ambient light sensor senses a low light condition for approximately 15 seconds, it will cancel DRL operation and turn on the headlamps at 100 percent intensity. A path to ground is provided to the coil of the DRL relay. With a direct path to ground provided to the headlamps though the closed contacts of the DRL relay and SP254 to G103, the headlamps will light at 100 percent intensity.