B2645

DTC B2645

CIRCUIT DESCRIPTION
The body control module (BCM) monitors the ambient light sensor signal circuit in order to determine if the daytime running lights (DRL) or the automatic lamp control (ALC) lamps should be turned ON in the AUTO mode. When the BCM senses the ambient light sensor voltage is between 1.75-4.9 volts, either the DRL will be commanded ON or the ALC will be commanded ON.

CONDITIONS FOR RUNNING THE DTC
The system voltage must be between 9.0-16.0 volts.

CONDITIONS FOR SETTING THE DTC
- When the ambient light sensor signal voltage is less than 1.75 volts.
- When the ambient light sensor signal voltage is more than 4.9 volts.

ACTION TAKEN WHEN THE DTC SETS
The ALC will remain ON in any ambient light state.

CONDITIONS FOR CLEARING THE MIL/DTC
- This DTC will clear immediately after the condition for setting the fault is corrected.
- A history DTC will clear after 100 consecutive ignition cycles without a fault present.
- Use a scan tool in order to clear history and current DTCs.

TEST DESCRIPTION

Steps 1-8:

Steps 9-14:

The numbers below refer to the step numbers on the diagnostic table.
3. Tests for the proper operation of the circuit in the low voltage range.
4. Tests for the proper operation of the circuit in the high voltage range. If the fuse in the jumper opens when you perform this test, the signal circuit is shorted to ground.
5. Tests for a short to voltage in the ambient light sensor low reference circuit.
13. After replacement of the BCM you must calibrate the new module for proper operation.