Volt

DTC B3650

For headlamp operation, the body control module (BCM) monitors three signal circuits from the indicator/multifunction switch. When the indicator/multifunction switch is in the AUTO position, the three signal circuits are open and the BCM relies on the ambient light sensor input to turn the headlamps and daytime running lamps (DRL) ON and OFF. When the indicator/multifunction switch is placed in the OFF position, the indicator/multifunction switch headlamps OFF signal circuit is grounded, indicating to the BCM that the exterior lamps should be turned OFF. With the indicator/multifunction switch in the SIDELIGHTS position, the indicator/multifunction switch sidelights ON signal circuit is grounded, indicating that the sidelights have been requested. When the indicator/multifunction switch is in the HEADLAMP position, both the indicator/multifunction switch sidelights ON signal circuit and the indicator/multifunction switch headlamps ON signal circuit are grounded. The BCM responds by commanding the sidelights and headlamps ON.

Battery voltage must be between 9-16V.

The BCM detects a short to ground in the indicator/multifunction switch main beam signal circuit.

The main beam headlamps will not operate.

Schematic Reference

Exterior Lamps Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Exterior Lighting Systems Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

1. Vehicle OFF, disconnect the harness connector at the S78 Indicator/Multifunction Switch.
2. Vehicle OFF, scan tool disconnected, all doors closed, all accessories OFF, and wait 2 minutes. Test for less than 10 Ω between the ground circuit terminal 6 and ground.

⇒	If greater then the specified range, test the ground circuit for an open/high resistance.

3. Vehicle in Service Mode, verify the scan tool Main Beam Select Switch parameter is Inactive.

⇒	If not the specified value, test the signal circuit terminal 11 for a short to ground. If the circuit tests normal, replace the K9 Body Control Module.

4. Install a 3 A fused jumper wire between the signal circuit terminal 11 and ground. Verify the scan tool Main Beam Select Switch parameter is Active.

⇒	If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K9 Body Control Module.

5. If all circuits test normal, replace the S78 Indicator/Multifunction Switch.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.