Daytime Running Lamp: Description and Operation

Electronic Daytime Running Light (DRL)

Junction Block Terminal Pins:

DESCRIPTION
The Combination Flasher/DRL is a module providing turn signal, hazard warning, and daytime running light functions (for Canadian vehicles), and has been designed with internal relays to take advantage of low current switching requirements in the vehicle. It is plugged into the junction block at positions three and four, where all wiring associated with its operation is terminated. The junction block is adjacent to and left of the steering column of the vehicle.

On vehicles built for use in the United States, only position four is used. Vehicles built for use in Canada utilize both positions three and four.

To gain access to the device, remove the lower steering column cover and knee blocker.

CIRCUIT OPERATION
On vehicles built for sale in Canada the turn signal lamps operate, when the ignition switch is in the ON position.

The lamps are controlled by the Body Control Module (BCM) and the combination electronic flasher/ Daytime Running Lamp (DRL) module. This module is located in the junction block.

Power for the module is supplied on circuit F20. This circuit is HOT in the RUN position only. Power for the F20 circuit is supplied on circuit A22/A2. This circuit is protected by a 40 Amp fuse located in cavity 2 of the Power Distribution Center (PDC).

Battery voltage for the DRL module is also supplied on circuit L9. This circuit is a direct battery feed and is protected by a 20 Amp fuse located in cavity 19 of the PDC.

Ground for the DRL module is supplied on circuit Z1, which terminates at the left cowl panel.

The DRL module is turned OFF when the operator turns ON the headlamps or applies the parking brake. Input for headlamps ON is supplied to the DRL module on circuit L93. Input for parking brake ON is supplied to the DRL on circuit L9.

To operate the lamps the DRL module controls the L60 circuit for the right front lamp, and the L61 for the left front lamp.

SYSTEM FUNCTION
The combination-flasher/DRL may be operated in its hazard warning mode either with or without the ignition circuit being active. However, in order to operate in the turn signal mode or the DRL mode, the ignition circuit must be completed to the module.

While the combination-flasher portion is idle, there is no current drawn through the module. The device does not become active in the turn signal or hazard warning modes until a signal ground circuit is supplied to either of the turn signal inputs or the hazard warning input. With the ignition OFF, there is no current drawn through the module.

While the ignition is ON, the front turn signal filaments are illuminated steadily thus providing the DRL function. The DRL function may be inhibited by applying a signal ground input from either the park brake circuit or the headlamp relay activation circuit.