B2575

DTC B2575





Circuit Description

The body control module (BCM) turns ON the headlamp relay when the ambient light sensor senses a dark condition. Battery positive voltage is supplied to the headlamp relay at all times through the BACKUP/TURN fuse. The BCM grounds the headlamp relay control circuit in order to activate the relay.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B2575 Headlamp Control Circuit

Conditions for Running the DTC

* The ignition switch is in the ON position.
* The ambient light sensor senses a dark condition, automatic lamp control (ALC) headlamps ON.

Conditions for Setting the DTC

The headlamp relay control circuit is open for 5 seconds.

Action Taken When the DTC Sets

The SERVICE indicator illuminates.

Conditions for Clearing the DTC

* The conditions for setting the DTC are no longer present.
* A history DTC clears after 100 malfunction-free ignition cycles.
* The BCM receives the clear code command from the scan tool.

Diagnostic Aids

* Turn the ignition switch to the OFF position, cover the ambient light sensor on the dash, wait for 15 seconds and then return the ignition to the ON position. The low beam headlamps should illuminate.
* If the DTC is a history DTC, the problem may be intermittent. Refer to Testing for Intermittent Conditions and Poor Connections. Component Tests and General Diagnostics

Test Description

Step 1 - Step 11:

The numbers below refer to the step numbers on the diagnostic table.
2. Listen for an audible click when the headlamp relay operates. Command both the ON and OFF states. Repeat the commands, as necessary.
3. Tests for voltage at the coil side of the headlamp relay. The BACKUP/TURN fuse supplies battery positive voltage to the coil side of the headlamp relay.
4. Verifies that the BCM is providing ground to the headlamp relay.