Daytime Running Lamp: Description and Operation

Daytime Running Lights Day Operation
When you turn the ignition to ON (II) with the parking brake released, the daytime running lights control unit supplies battery voltage at the WHT/RED wire. This voltage is applied to the high beam headlights through the daytime running lights resistor. Each high beam headlight receives less than battery voltage causing them to come ON at reduced brightness.
If the parking brake is set, a ground signal is applied to the daytime running lights control unit at the RED/GRN wire. If the parking brake is set when you first turn the ignition switch to ON (II), the high beam headlights will remain OFF until you release the parking brake. Once the high beam headlights are in day mode, setting the parking brake will not cause the headlights to turn OFF. When low or high beam operation is requested, battery voltage from the headlight switch is applied to the daytime running light control unit via the RED/WHT wire. The daytime running light control unit then discontinues the daytime running light mode.