For 1990-2009 cars

### Circuit Description

When the body control module (BCM) receives a ground signal from the headlamp switch commanding to illuminate the park lamps, the BCM will energize the park lamp relay by grounding the park lamp relay control circuit.

### DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B2585 Park Lamp Control Circuit

### Conditions for Running the DTC

The battery voltage must be between 9-16 volts.

### Conditions for Setting the DTC

• | When the BCM receives a park lamp OFF command and the park lamp relay control circuit is shorted to ground

• | When the BCM receives a park lamp ON command and the park lamp relay control circuit is shorted to voltage or open

### Action Taken When the DTC Sets

The park lamps will not operate or will remain always ON.

### Conditions for Clearing the MIL/DTC

• | This DTC will clear on current status after the condition for setting the fault is corrected.

• | A history DTC will clear after 100 consecutive ignition cycles without a fault present.

• | History and current DTCs can be cleared using a scan tool.

### Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. Listen for an audible click when the park lamp relay operates. Command both the ON and OFF states. Repeat the commands as necessary.

2. This step tests for voltage at the coil side of the park lamp relay.

3. This step verifies that the BCM is providing ground to the park lamp relay.

4. This step tests if ground is constantly being applied to the park lamp relay.

5. This step tests if there is opposing voltage present or an open park lamp relay control circuit.

6. After replacement of the BCM, you must calibrate the new module for proper operation.

Step | Action | Yes | No
--- | --- | --- | ---
Schematic Reference: Exterior Lights Schematics Connector End View Reference: Lighting Systems Connector End Views or Data Communication Connector End Views
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 |

1. Install a scan tool.
2. Turn ON the ignition, with the engine OFF.
3. With a scan tool, command the park lamp relay ON and OFF.

Does the park lamp relay turn ON and OFF with each command?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3 |

1. Turn OFF the ignition.
2. Disconnect the park lamp relay.
3. Turn ON the ignition, with the engine OFF.
4. Probe the battery positive voltage circuit of the park lamp relay with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

Go to Step 4

Go to Step 10

4 |

1. Connect a test lamp between the control circuit of the park lamp relay and the battery positive voltage circuit of the park lamp relay.
2. With a scan tool, command the park lamp relay ON and OFF .

Does the test lamp turn ON and OFF with each command?

Go to Step 8

Go to Step 5

5 | Does the test lamp remain illuminated with each command? | Go to Step 7 | Go to Step 6
6 | Test the control circuit of the park lamp relay for a short to voltage or an open. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 13 | Go to Step 9
7 | Test the control circuit of the park lamp relay for a short to ground. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 13 | Go to Step 9
8 | Inspect for poor connections at the park lamp relay. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 13 | Go to Step 11
9 | Inspect for poor connections at the harness connector of the body control module (BCM). Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 13 | Go to Step 12
10 | Repair the battery positive voltage circuit of the park lamp relay. Refer to Wiring Repairs . Did you complete the repair? | Go to Step 13 | --
11 | Replace the park lamp relay. Refer to Relay Replacement . Did you complete the replacement? | Go to Step 13 | --
12 | Replace the BCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 13 | --
13 |

1. Use the scan tool in order to clear the DTCs .
2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

Go to Step 2

System OK