B2647

DTC B2647

CIRCUIT DESCRIPTION
The Body Control Module (BCM) uses the ambient light sensor signal to control the automatic headlamp control system and the Daytime Running Lamps (DRL). The ambient light sensor is connected directly to the BCM through the DRL ambient light sensor signal circuit and the DRL ambient light low reference circuit.

CONDITIONS FOR RUNNING THE DTC
The DRL feature or the automatic headlamp control feature must be enabled.

CONDITIONS FOR SETTING THE DTC
- The BCM detects a short to ground in the DRL ambient light sensor signal circuit.
- The ambient light sensor is internally shorted.
- The condition above must be present for more than 0.3 seconds.

ACTION TAKEN WHEN THE DTC SETS
- The BCM stores DTC B2647 in memory.
- The DRL will default to night mode and the headlamps, park lamps, tail lamps and side marker lamps will illuminate.

CONDITIONS FOR CLEARING THE DTC
- The BCM no longer detects a short to ground in the DRL ambient light sensor signal circuit.
- A history DTC B2647 will clear after 100 consecutive ignition cycles if the condition for the malfunction is no longer present.
- The BCM receives a clear code command from the scan tool.

DIAGNOSTIC AIDS
- If the DTC B2647 is a history DTC, the fault may be intermittent.
- The following conditions may cause an intermittent malfunction to occur:
- An intermittent short to ground in the DRL ambient light sensor signal circuit
- The ambient light sensor is intermittently shorted.
- The BCM is intermittently shorted to ground.

TEST DESCRIPTION

Steps 1 - 3:

Steps 4 - 7:

Steps 8 - 12:

The numbers below refer to the step numbers on the diagnostic table.
3. Tests for the proper operation of the circuit in the high voltage range.
4. Tests for the proper operation of the circuit in the low voltage range. If the fuse in the jumper opens when you perform this test, the signal circuit is shorted to battery positive voltage.