Lighting

CIRCUIT CHART

Circuit Chart:

Circuit assignments for the Body Control Module (BCM) relating to lighting:

DISPLAY DIMMING
Display dimming is controlled by the BCM based on input received from the dimming potentiometer. The dimming potentiometer is connected between circuit 719 and circuit 230. The BCM monitors these inputs and provides a Pulse Width Modulated (PWM) output at circuit 8 to operate the display lamps.

PARK LAMP SWITCH
The BCM compares the state of the park lamp circuit 9 to the high beam headlamp circuit 1200 and the low beam headlamp circuit 1201.

If the park lamp circuit is grounded/open and either the low beam circuit is at battery voltage or the high beam circuit is grounded, DTC B2662 - Parklamp Switch Circuit Malfunction will set.

DAYTIME RUNNING LAMPS
Daytime Running Lamps (DRL) are controlled by the BCM based on input from the high beam headlamp circuit 1200, the low beam headlamp circuit 1201, the parking brake circuit 1134 and ignition switch state.

When DRL operation is desired, the BCM switches circuit 592 to ground. This action energizes the DRL relay. When energized, the DRL relay operates the left high beam headlamp and right high beam headlamp as a series circuit (one-half of battery voltage across each high beam headlamp).

When DRL operation is not desired, the BCM does not provide ground for the DRL relay. When not energized (as when high beam headlamps are desired) the DRL relay operates the right and left high beam headlamps as a parallel circuit (full battery voltage across each high beam headlamp).

Daytime Running Lamps:

For DRL operation, the parking brake must be fully released, the ignition switch must be in the RUN position and headlamp switch must be in the Off position. On automatic transaxle vehicles the vehicle must be shifted out of Park to activate the DRL's. Under normal operating conditions, the feedback voltage to the BCM measured at circuit 1200 is:

DOME/REAR READING LAMPS
Dome and rear reading lamp operation is through the Body Control Module (BCM) providing ground to circuit 156. When manually operated by their respective local switches, the dome and rear reading lamps are grounded through circuit 450 and the right body ground splice pack.

BATTERY RUNDOWN PROTECTION

NOTE: If the dome lamp is not in the DOOR position the battery rundown protection feature does not function.

Battery rundown protection is controlled by the BCM when the dome lamp is in the DOOR position. If the dome lamp is on an extended amount of time due to a hatch being left open the BCM will turn Off the output for the dome lamp after 20 minutes to conserve battery energy. If the odometer is less than 24 km (15 miles), the dome lamp will be turned Off in 3 minutes. When the odometer is over 24 km (15 miles) the timer will change to 20 minutes.