B2575

DTC B2575

CIRCUIT DESCRIPTION
The body control module (BCM) grounds the headlamp relay control circuit when the ambient light sensor senses a dark condition. Voltage is supplied to the headlamp relay when the ignition is in the RUN position.

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 RUN position.
- The ambient light sensor senses a dark condition.
- The headlamp switch is in the AUTO position.
- Transmission gear selectors not in the PARK position.

CONDITIONS FOR SETTING THE DTC
Any of the following conditions will set this DTC:
- The headlamp relay control circuit is open for 5 seconds.
- The headlamp relay coil is open.
- Ignition voltage to the headlamp relay is open.
- The low beam signal circuit is open between the headlamp switch and the instrument panel (I/P) fuse block.
- The headlamp relay output circuit is open.
- The ground is open to the headlamp relay or switch.

ACTION TAKEN WHEN THE DTC SETS
The headlamps will not illuminate in the AUTO position.

CONDITIONS FOR CLEARING THE DTC
- The BCM receives the clear code command from the scan tool.
- A current DTC will clear when the conditions for setting the DTC are no longer present.
- A history DTC clears after 100 malfunction free ignition cycles.

DIAGNOSTIC AIDS
- Turn the ignition switch to the OFF position, cover the ambient light sensor on the instrument panel, wait for 15 seconds and then return the ignition to the ON position. The headlamps should illuminate.
- If the DTC is a history DTC, the problem may be intermittent.
- An open in the following circuits may cause DTC B2575:
- Low beam signal circuit
- Headlamp relay output circuit
- Ground to the headlamp switch or relay

TEST DESCRIPTION

Step 1 - Step 11:

Step 12 - Step 15:

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