For 1990-2009 cars

### Headlight Operation (Buick)

Battery positive voltage (B+) is supplied to the lamp control module (LCM) through the right rear fuse block HDLP circuit breaker via CKT 1740 at all times. The circuit breaker opens if the headlight circuit draws too much current. When open, the circuit breaker interrupts the current flow. With no current flow, the circuit breaker cools and resets automatically. With the headlamp switch in the ON position, battery positive voltage (B+) is supplied from the LCM to the low beam headlamps. Pull the multi-function lever (turn signal) towards the driver in order to enable the high beam operation. This signals the LCM to remove the battery positive voltage (B+) from the low beam headlamps and supply battery positive voltage (B+) to the high beam headlamps.

### Headlight Operation (Oldsmobile)

Battery positive voltage (B+) is supplied to the lamp control module (LCM) through the right rear fuse block HDLP circuit breaker via CKT 1740 at all times. The circuit breaker opens if the headlight circuit draws too much current. When open, the circuit breaker interrupts the current flow. With no current flow, the circuit breaker cools and resets automatically. With the headlamp switch in the ON position, battery positive voltage (B+) is supplied through the headlamp dimmer switch to the low beam headlamps. Pull the multi-function lever (turn signal) towards the driver in order to enable the high beam operation. Battery positive voltage (B+) is then supplied from the LCM through the headlamp dimmer switch to the high beam headlamps.

### Flash-To-Pass (Buick)

When the multi-function lever (turn signal) is pulled towards the driver, a signal is sent to the lamp control module (LCM) to supply battery positive voltage (B+) to the high beam headlamps for as long as the lever is held. If the low beam headlamps are on when the lever is pulled, the headlamps switch to the high beams. The high beams remain on until the lever is pulled again. If the high beam headlamps are on when the lever is pulled, the headlamps switch to the low beams. The low beams remain on until the lever is pulled again

### Flash-To-Pass (Oldsmobile)

Battery positive voltage (B+) is applied through the engine compartment fuse block FOG LAMP fuse via CKT 42 (RED) at all times to the headlamp dimmer switch. When the multi-function lever (turn signal) is pulled towards the driver, battery positive voltage (B+) is applied through the headlamp dimmer switch to the high beam headlamps via CKT 11 (LT GRN). If the headlamps are off, pulling the lever will turn the high beam headlamps on for as long as the lever is held. Releasing the lever turns the headlamps off. If the low beam headlamps are on when the lever is pulled, the headlamps switch to the high beams. The high beams remain on until the lever is pulled again. If the high beam headlamps are on when the lever is pulled, the headlamps switch to the low beams. The low beams remain on until the lever is pulled again.

### Ambient Light Sensor

The lamp control module (LCM) monitors ambient light conditions through the ambient light sensor. The ambient light sensor is a variable resistor. The sensor resistance changes as the ambient light level changes. As the ambient light decreases, the resistance of the ambient light sensor increases. The LCM measures the voltage across the ambient light sensor in order to determine the ambient light conditions.

### Perimeter Lighting

The perimeter lighting provides a personal security feature by illuminating all of the exterior lights on the vehicle exterior for 15 seconds when the keyless entry transmitter is used in order to unlock the doors at night. The following lamps will be illuminated:

• | The backup light

• | The headlights

• | The park lights

• | The cornering lights

When the UNLOCK button on the keyless entry transmitter is pressed, the remote function actuator (RFA) module grounds CKT 624 (BLK/WHT) to the lamp control module (LCM) perimeter lighting input. The LCM then provides battery positive voltage (B+) to the headlamps and to the park lamps. Battery positive voltage (B+) is supplied through the instrument panel (IP) fuse block PERIM LP fuse and CKT 1654 (TAN) to the perimeter lighting relay. The RFA provides ground for the perimeter lighting relay through CKT 1655 (DK GRN). The coil is energized and the switch contacts close. This provides battery positive voltage (B+) to the backup lights and to the cornering lights.