Daytime Running Lamps

Daytime running lamps are standard on all Saturn models. The DRL relay is located in the Underhood Fuse Block (UHFB). The coil side of the DRL relay receives battery voltage. Current flows through the DRL relay coil to the body control module through circuit 592. The BCM will ground circuit 592 when DRL is required. The BCM uses ignition, park lamp, headlamp, high beam and park brake inputs to control DRL. The DRL will be enabled anytime the ignition is in the RUN position, the headlamp switch is Off and the park brake switch is Off (park brake not engaged).

Battery voltage is supplied through the left headlamp fuse to circuit 40 to the left high beam lamp. Voltage flows through the left high beam lamp to the UHFB through circuit 1200. Current flows to the right high beam lamp from the UHFB through circuit 1200. Current flows through the right high beam lamp to the DRL relay located in the UHFB through circuit 593. The BCM provides ground to circuit 592 to energize the relay. Current flows through the closed contacts of the DRL relay to ground through circuit 150 to the forward lamp splice pack. This circuit results in both high beam lamps being connected in series, which allows the high beam lights to operate at half brightness.

The BCM will turn Off the DRL relay when it sees any of the following inputs:
- Headlamps On
- Parking brake On
- Ignition not in the RUN position

The BCM uses the high beam input to determine if the DRL functions are working. If the DRL functions are not operating properly a diagnostic trouble code may be set. Refer to Diagnosis in this section for further information.