Headlights With Twilight Sentinel

CIRCUIT OPERATION:
The Body Computer Module (BCM) controls the Twilight Sentinel system by controlling the Twilight Sentinel Park Lamp Relay and the Twilight Sentinel Headlamp Relay.

The BCM energizes both relays by grounding circuit 692 at terminal 1D4 when the Ignition Switch is in RUN, the Twilight Sentinel Switch is "ON" and the Twilight Photocell indicates low ambient light. When the Twilight Sentinel Switch is "ON," BCM terminal 2B5, the Twilight Enable Input, is grounded through the Left Switch Assembly. Ambient light conditions are monitored by the BCM at terminal 3C7, the Twilight Photocell Input. The Twilight Sentinel Park Lamp Relay supplies voltage through circuit 9 to the Park Lights when energized and the Twilight Sentinel Headlamp Relay supplies voltage through circuit 12 to the Headlights circuit when energized.

The BCM will keep the Twilight Relays energized for an adjustable time period (up to 3 minutes) after the Ignition Switch is turned "OFF" when in the Twilight Sentinel mode. The Twilight Delay is determined by the voltage level at BCM terminal 3C1, the Twilight Delay Input. The voltage level is varied by adjusting the Twilight Sentinel Switch between MIN and MAX.

During CRANK, BCM control of the Twilight Relays is disabled. The Twilight Crank Relay keeps the Twilight Relays energized during CRANK when in the Twilight Sentinel Mode. After the engine starts, the BCM will again control the Twilight Relays.