Circuit Operation

The headlamps are controlled by the Daytime Running Lamps (DRL) Control Module and the Headlamp/Dimmer Switch. With the switch in the "HEAD" position and the Dimmer Switch in LO, ground is provided to the low beam filaments through the Dimmer Switch and the closed contacts of the Headlamp Relay 1 to G201. Since voltage is supplied to the headlamps at all times through the LEFT HEADLAMP Fuse and the RIGHT HEADLAMP Fuse, the low beam filaments will light.

With the Dimmer Switch in the "HI" position, the high beam filaments in the headlamps are grounded through the Dimmer Switch, through the closed contacts of the Headlamp Relay 1 to G201. Since voltage is applied to the headlamps at all times through the LEFT HEADLAMP Fuse and the RIGHT HEADLAMP Fuse, the high beam filaments will light. The ground to the High Beam Indicator is provided in the same manner as the high beam filaments. Since voltage is supplied to the High Beam Indicator at all times through the LEFT HEADLAMP Fuse, the indicator will also light.

With the Dimmer Switch in the "PASS" position, the high beam filaments in the headlamps are grounded through the Dimmer Switch and Headlamp Relay 1 to G201. Since voltage is applied to the headlamps at all times through the LEFT HEADLAMP Fuse and the RIGHT HEADLAMP Fuse, the high beam filaments will light. The ground to the High Beam Indicator is provided in the same manner as the high beam filaments. Since voltage is supplied to the High Beam Indicator at all times through the LEFT HEADLAMP Fuse, the indicator will also light.

With the Ignition Switch in "ON" or "START," voltage is applied to the DRL Control Module through the IG-COIL METER Fuse. The DRL Control Module is permanently grounded to G200. A number of conditions must be met before the Daytime Running Lamps system will work properly:
^ The parking brake must be disengaged.
^ The DRL Control Module must not receive a ground signal from the Generator (a ground signal from the generator indicates that the generator is not charging the battery).
^ The Headlamp/Dimmer Switch is either in "OFF" or in PARK position.

When the parking brake is engaged, the Parking Brake Switch closes, providing a ground to the DRL Control Module, disabling DRL operation. When the Generator is not running, a switch in the Generator closes, providing a ground to the DRL Control Module. disabling DRL operation. When the Headlamp/Dimmer Switch is in the "HEAD" position, a path to G201 is provided to the coil of Headlamp Relay 1 and the DRL Control Module, disabling DRL operation.

Once all of the listed conditions for DRL operation are met, the DRL Control Module will provide a ground for the low beam filaments in the headlamps through the DRL Control Module to G200. Since voltage is applied to the headlamps at all times through the LEFT HEADLAMP Fuse and the RIGHT HEADLAMP Fuse, the low beam filaments will light at 80% intensity.

The DRL Control Module will also provide a ground to the Daytime Running Lamps Indicator when the DRL operation conditions are met. Since voltage is applied to the Daytime Running Lamps Indicator through the IG-COIL METER Fuse, it will light.