B2585

Circuit Description
The BCM monitors the voltage on CKT 2409 in order to determine the actual state of the park lamp relay.

The BCM also uses CKT 1080 to energize the park lamp relay. The BCM will set a related DTC when the voltage on the following circuits is low:
- CKT 1080
- CKT 2409

Conditions for Setting the DTC
- The ignition is in the RUN position.
- The park brake is released.
- The headlamp and panel dimmer switch is in the AUTO mode.
- The ambient light sensor is in the DARK state.
- There is an open in CKT 2409 or CKT 1080.
- There is an open in CKT 2409. The DTC will set regardless of the setting of the headlamp and panel dimmer switch.
- There is an open in CKT 1080 and the headlamp and panel dimmer switch is in the AUTO mode.
- The system voltage is between 9.0 - 16.0 volts.
- The above conditions exist for 0.5 seconds.

Action Taken When the DTC Sets
- The park lamps will be disabled.
- The instrument panel back lights remain ON at all times when CKT 2409 is open.

Conditions for Clearing the MIL/DTC
- A current DTC will clear after the next ignition cycle that does not contain a fault.
- A history DTC will clear after 100 consecutive ignition cycles without a fault present.
- History and current DTCs may be cleared using a scan tool.

Diagnostic Aids
- Use an incandescent shop light or a flashlight. Direct the lighting toward the light sensor in order to force the sensor into a LIGHT state.
- Always diagnose the first DTC that is listed on the scan tool.
- Verify that the scan tool displays DTC B2585 as a current code before you perform diagnostics.
- Inspect for loose or poor connections at all of the related components.
- Refer to Intermittents and Poor Connections Diagnosis in Overall Vehicle Information / Testing and Inspection.

Steps 1 - 4:

Steps 5 - 8:

Steps 9 - 12:

Steps 13 - 20:

Steps 21 - 25:

Test Description
The numbers below refer to the step numbers on the diagnostic table.
2. This step determines if the light sensor turns ON the headlamp.
3. This step tests the PARK LP fuse.
5. This step tests for an open in CKT 1080.
6. This step tests the park lamp relay.
17 .This step tests for a short to ground in CKT 2409.