DTC B2648: Ambient Light Sensor Circuit High: Description

The ambient light sensor provides input to Body Control Module (BCM) to control Daytime Running Light (DRL) operation. BCM provides 5 volt reference on circuit No. 1138 (Yellow/Black wire) and ground signals on circuit No. 1137 (Light Green/Black wire) to ambient light sensor. When ambient light is high, BCM will receive high voltage from ambient light sensor through Light Green/Black wire. When ambient light is low, BCM will receive low voltage from ambient light sensor through Light Green/Black wire.

BCM monitors ambient light sensor voltage signal to determine if return voltage is within range. DTC B2648 will set if a short to voltage in one of the ambient light sensor circuits exists for a minimum of 2 seconds.

When DTC B2648 sets in BCM, DRLs will remain on at all times and no driver warning message will be displayed. If conditions for malfunction no longer exist, history DTC will clear after 50 consecutive ignition cycles. DTC B2648 will also clear when conditions no longer exist, or when Instrument Panel Cluster (IPC) or scan tool is used to clear codes.

NOTE: If DTC B2648 is a history code, problem may be intermittent. Wiggle wires while performing the following test.