With Daytime Running Lights (DRL)

With the Ignition Switch in "RUN," the Headlight Switch not in "HEAD" and the Park Brake released, the Daytime Running Lights (DRL) Module grounds the coil of the DRL Relay. The relay is energized, and battery voltage is applied to the ground side of the LH Headlights, allowing voltage also to be applied to the RH Headlights. This series circuit arrangement causes the voltage across each Headlight to be exactly half of the battery voltage, reducing Headlight brilliance for the DRL mode operation.

When the Headlight Switch is in "HEAD" and the Headlight Dimmer Switch is in "LO," battery voltage is applied to the LO Beam Input of the DRL Module via CKT 12. The module de-energizes the DRL Relay, applying ground to the LH Headlight. Battery voltage is applied to the LO Beam Headlight's filaments via CKT 12.

When the Headlight Switch is in "HEAD" and the Headlight Dimmer Switch is in "HI," battery voltage is applied to the HI Beam Input of the DRL Module via CKT 11. The Module de-energizes the DRL Relay, removing voltage from CKT 593 and disengaging DRL mode operation. With the relay de-energized, the ground path through the DRL Relay to the LH HI Beam Headlight is restored. Battery voltage is applied to the Hi Beam Headlights via CKT 11.

The Fog Light Switch receives battery voltage from the TAIL LPS Fuse. With the Headlight Switch in "PARK" or "HEAD," battery voltage is applied to the Fog Light Switch through the INST LPS Fuse. With the LO Beam Headlights on and the Fog Light Switch "ON," battery voltage is applied to the coil of the Fog Light Relay. The Fog Light Relay coil receives its ground signal through the DRL Module. The relay is energized, and voltage from Fusible Link E is applied to the Fog Lights through the Fog Light Relay contacts. If the HI Beam Headlights are turned on, battery voltage is applied to the HI Beam Input of the DRL Module. The DRL Module removes ground from the Fog Light Relay, and the relay is de-energized, removing battery voltage from the Fog Lights.

The Daytime Running Lights (DRL) Module has an input from the BRAKE Indicator control circuit. When the Park Brake is set, ground is applied to the DRL Module Park Brake Applied Input. The DRL Module then removes ground from the DRL Relay, and the relay is de-energized, removing battery voltage from the Headlights. Because the Park Brake Switch shares CKT 33 with the Electronic Brake Control Module (EBCM) and the Brake Fluid Level Switch, any condition that causes the BRAKE Indicator to come on will also inhibit the Headlights from operating in Daytime Running Lights mode.