Battery Discharge Protection Relay: Description and Operation

CIRCUIT OPERATION
The headlamp delay uses a relay located in the junction block. Power for the relay is supplied on circuit A3. This circuit powers the coil and contact sides of the relay and is protected by a 30 Amp fuse located in the Power Distribution Center (PDC) cavity H.

The relay is activated by the operator turning OFF the ignition with the headlamps ON. The Body Control Module (BCM) receives this input on the G52 circuit from the headlamp switch. The BCM controls the ground for the coil side of the relay and the amount of time the headlamps stay ON. Circuit G50 connects the coil side of the relay to the BCM.

When the relay is energized, the contacts in the relay close connecting circuits A3 and L2. Circuit L2 is used to supply power to the beam select switch. Circuit L4 connects from the beam select switch to the fuses that power low beam headlamps.