B2648

DTC B2648






Circuit Description

The body control module (BCM) uses the ambient light sensor signal to control the daytime running lamps (DRL). The ambient light sensor is connected directly to the BCM.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B2648 Ambient Light Sensor Circuit High

Conditions for Running the DTC

* The system voltage must be between 9-16 volts.
* The ignition switch must be in the RUN position.
* The park brake must be released.
* The headlamp switch must be in the AUTO position.
* The DRL feature must be enabled.

Conditions for Setting the DTC

* When the ambient light sensor input voltage is greater than 4.78 volts
* The courtesy lamp relay coil control circuit is shorted to the battery.
* The above conditions must be met for 0.5 seconds.

Action Taken When the DTC Sets

* The DRL will remain ON.
* The BCM stores DTC B2648 in memory.
* Exterior lamps illuminate to low light intensity.

Conditions for Clearing the MIL/DTC

* A current DTC B2648 clears when the BCM no longer detects the fault in the signal circuit or the low reference circuit of the DRL ambient light sensor.
* A history DTC B2648 clears after 100 consecutive ignition cycles.
* The BCM receives the Clear Code command from the scan tool.

Diagnostic Aids

* If the DTC B2648 is a history DTC, the fault may be intermittent. Refer to Testing for Intermittent Conditions and Poor Connections. Component Tests and General Diagnostics
* An intermittent short to voltage or an open in the following locations may cause an intermittent malfunction to occur:

- The low reference circuit of the DRL ambient light sensor
- The sensor circuit of the DRL ambient light sensor
- The ambient light sensor
- The BCM

Test

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