B2648

DTC B2648 Ambient Light Sensor Circuit High:

CIRCUIT DESCRIPTION
DTC B2648 (both current and history) indicates a short to battery 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 analog input is shorted to B+ for 5 seconds.

ACTION TAKEN WHEN THE DTC SETS
^ Stores DTC B2648 in the Body Control Module (BCM) memory.
^ The SERVICE VEHICLE SOON indicator illuminate.
^ The check gauges chime sounds.

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 DTCs 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 battery in CKT 1138 between the Body Control Module (BCM) and the Ambient Light Sensor.