For 1990-2009 cars
Body Control Module Components
Cell 51: Low Beam and Park Lamp Relays
Handling ESD Sensitive Parts Notice

### Circuit Description

When the ignition is in the ON position, the body control module (BCM) supplies exterior lamp power to the high side of the park lamp relay coil. The BCM grounds the coil at terminal C12, energizing the relay, when the BCM receives an input to turn the park lamps ON. This allows battery power to be supplied to the park lamps.

### Conditions for Setting the DTC

The BCM monitors the output to the park lamp relay every second at terminal C12. The criteria for the fault code to set is as follows:

• | Exterior lamp power is active.

• | A DTC B1970 is not set.

• | The headlamp switch is inactive.

• | The commanded state doesn't match the feedback for 3 seconds (open circuit, short to ground or B+).

### Action Taken When the DTC Sets

• | The BCM continues to command the requested state until the state is achieved or until the state changes.

• | Stores a DTC B2476 in the BCM memory.

### Conditions for Clearing the DTC

• | The conditions for the fault are no longer present.

• | The use of a scan tool.

• | A history DTC will clear after 50 ignition cycles if the conditions for the fault is no longer present.

### Diagnostic Aids

Refer to Power and Grounding Component Views in Wiring Systems for an end view and for terminal assignments of the relay box when the diagnostics direct you to take electrical measurements at the relay box.

Test for the following conditions if a history or intermittent DTC is indicated:

• | A damaged wiring harness. Inspect the wiring harness for damage. If the wiring harness appears to be in good condition, observe the display on the DMM while moving the connectors and wiring harnesses related to the circuits. A change in the DMM display during this test will indicate the location of the fault.

• | For additional information, refer to Intermittents and Poor Connections Diagnosis .

• | A short to ground in circuit XM810 may cause the park lamps to illuminate at all times with the ignition ON and the headlamp switch in the OFF position.

### Test Description

The following numbers refer to the step numbers on the diagnostic table:

1. This step uses a scan tool to test the park lamp operation and to verify if the fault is present.

2. This step tests for an intermittent condition in the circuits that can cause a DTC B2476 to set.

3. After verifying that no circuit problems exist, the BCM is most likely at fault. The BCM needs to be programmed after installation.

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the BCM System Check? | -- | Go to Step 2 | Go to Diagnostic System Check - Body Control System
2 |

1. Connect the scan tool to the data link connector (DLC).
2. Select PARK LAMPS from the Light Test Menu in Special Functions.
3. Press the ON button then press the OFF button and monitor park lamp operation.

Did the park lamps light when commanded ON?

--

Go to Step 3

Go to Step 4

3 |

1. Problem is not current at this time. Test terminal C12 connector C2 of the BCM for a poor connection.
2. Test CKT XM810 (BRN/WHT) for an intermittent open, short to ground or voltage.
3. Test CKT AM810 (RED/WHT) for an intermittent open.

Is the repair complete?

--

Go to Step 12

--

4 |

1. Disconnect BCM connector C2.
2. Turn the park lamps ON at the switch.
3. Use a DMM in order to measure the voltage at terminal C12.

Is the measured voltage at the specified value?

B+

Go to Step 5

Go to Step 6

5 |

1. Remove the park lamp relay from the relay box.
2. Remeasure the voltage at terminal C12.

Is the voltage at terminal C12 less than the indicated value?

1 V

Go to Step 11

Go to Step 10

6 |

1. Disconnect BCM connector C1.
2. Measure the resistance from connector C1 terminal B10 to connector C2 terminal C12.

Was an open found?

--

Go to Step 8

Go to Step 7

7 | Measure the resistance from BCM connector C2 terminal C12 (CKT XM810) to a good ground. Is the measured resistance at the specified value? | OL | Go to Step 12 | Go to Step 9
8 | Locate and repair the open circuit in CKTs AM810 or XM810. Is the repair complete? | -- | Go to Step 12 | --
9 | Locate and repair the short to ground in CKTs XM810 or XM815. Is the repair complete? | -- | Go to Step 12 | --
10 | Locate and repair the short to B+ in CKTs XM810 or XM815. Is the repair complete? | -- | Go to Step 12 | --
11 | Important: Perform the set up procedure for the BCM. Replace the BCM. Refer to Body Control Module Replacement . Is the replacement complete? | -- | Go to Step 12 | --
12 |

1. Install the scan tool in order to clear any BCM DTCs.
2. Verify proper park lamp operation.
3. Recheck for DTC B2476.

Did a current DTC B2476 set?

--

Go to Step 2

System OK