Daytime Running Lamp Control Unit: Description and Operation

CANADIAN VEHICLES
On Canadian vehicles, the low-beam headlamps operate when the ignition switch is in the RUN position and the headlamp switch is OFF.

When the ignition switch is in the START or RUN positions, circuit A1 from fuse 4 in the Power Distribution Center (PDC) connects to circuit A21. Circuit A21 supplies voltage to circuit G5 through fuse 9 in the fuse block. Circuit G5 splices to supply battery voltage to the Daytime Running Lamp (DRL) module.

Circuit L20 from the headlamp switch connects to the DRL module. Circuit L20 is HOT at all times.

The DRL module receives the vehicle speed sensor input from circuit G7. Circuit G34 from the DRL module provides power for the high beam indicator lamp in the instrument cluster.

Circuit L4 feeds the low beams of the headlamps. When the headlamp switch is in the OFF position, the DRL module powers the left and right headlamps on circuit L4. When the headlamps are ON, the dimmer switch powers the low beams on circuit L4.

Circuit L3 feeds the high beams of the headlamps. When the operator flashes the high beams with the turn signal stalk, the DRL senses voltage on circuit L3. When it senses voltage on circuit L3, the DRL module stops supplying power to the low beams on circuit L4.

Circuit Z1 provides ground for the DRL module. Circuit Z1 terminates at the radiator left side support.