B2647

DTC B2647 Ambient Light Sensor Circuit Low:

CIRCUIT DESCRIPTION
DTC B2647 (both current and history) indicates a short to ground or open in the ambient light sensor signal circuit.

CONDITIONS FOR SETTING THE DTC
All of the following conditions must be met:
^ The Automatic Lighting Control (ALC) option is enabled.
^ Ignition 1 is active.
^ The ambient light sensor is shorted for 5 seconds.

ACTION TAKEN WHEN THE DTC SETS
^ The headlamps are always on at full intensity.
^ Stores DTC B2647 in the Body Control Module (BCM) memory.

CONDITIONS FOR CLEARING THE DTC
^ The BCM goes to sleep and reinitializes with the fault cleared.
^ All BCM history codes clear after 100 ignition cycles (from OFF to ON) with no current codes active.
^ Clear history and current DTC(s) using a Scan Tool scan tool.

DIAGNOSTIC AIDS
If the DTC is a history DTC the problem may be intermittent. Perform the above tests while wiggling the wiring and connectors. This may often cause the malfunction to appear.

TEST DESCRIPTION
The numbers below refer to the step numbers in the diagnostic table.
2. This step determines a short to ground in CKT 1138 between the Body Control Module (BCM) and the ambient light sensor.
4. This step determines an open in CKT 1138 between the Body Control Module (BCM) and the Ambient Light Sensor.