Daytime Running Lamp Control Unit: Description and Operation

CIRCUIT OPERATION - LEFT HAND DRIVE
On vehicles built for sale in Canada, the low-beam headlamps operate when the ignition switch is in the RUN position.

When the ignition switch is in the START or RUN position, circuit A1 from fuse 8 in the Power Distribution Center (PDC) connects to circuit A21. Circuit A21 splices to supply power to the DRL module.

Circuit A3 from fuse 13 in the PDC connects to DRL module. Circuit A3 is HOT at all times.

The DRL module receives the vehicle speed sensor input from circuit G7. Circuit G465 from the DRL module splices to circuit L3 to provide power for the high beam indicator lamp in the instrument cluster.

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

Circuit L3 feeds the high beams of the headlamps. When the operator flashes the headlamps with the stalk of the multi-function switch, the DRL senses voltage on circuit L3.

Circuit Z1 provides ground for the DRL module.