GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The body control module (BCM) controls the backup lamp relay. The BCM grounds the backup lamp relay control circuit energizing the backup lamp relay. The BCM connects directly to the center console fuse block with no external wiring between them.

Conditions for Running the DTC

Any of the following conditions may be present.

    • The transaxle is not in the REVERSE position.
    • The ignition switch is not in the OFF position.

Conditions for Setting the DTC

    • The fault code will set when the backup lamp relay control circuit is inactive and a short to ground or open is present.
    • The condition above must be present for more than 0.3 seconds.

Action Taken When the DTC Sets

The backup lamps will not illuminate, or will remain ON.

Conditions for Clearing the DTC

    • A current DTC will clear if the BCM no longer detects a short to ground or open in the backup lamp relay control circuit.
    • A history DTC will clear after 100 consecutive ignition cycles if the condition for the malfunction is no longer present.
    • Current and history DTCs can be cleared when the BCM receives a clear code command from a scan tool.

Diagnostic Aids

    • If the DTC is a history DTC, the fault may be intermittent. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
    • The following conditions may cause an intermittent malfunction to occur:
       - An intermittent short to ground or open in the backup lamp control circuit.
       - The backup lamp relay coil is intermittently shorted to ground or open.
       - The BCM is intermittently shorted to ground or open.

Test Description

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

  1. Tests if ground is constantly being applied to the backup lamp relay.

Step

Action

Yes

No

Schematic Reference: Exterior Lights Schematics

Connector End View Reference: Master Electrical Component List in Wiring Systems

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Lighting Systems

2

Important: This DTC may set under normal operating conditions. If the Backup Lamp System operates properly and there is no customer complaint related to the Backup Lamp System, do not continue with this diagnostic procedure.

  1. Block the drive wheels
  2. Press the brake pedal
  3. Place the gear selector in the REVERSE position and back to the PARK position.

Do the backup lamps operate as expected?

Go to Diagnostic Aids

Go to Step 3

3

Is the TRN SIG fuse in the console fuse block open?

Go to Step 7

Go to Step 4

4

  1. Disconnect the backup lamp relay.
  2. Connect a test lamp between the ignition voltage circuit, coil side and the backup control circuit of the backup lamp relay connector.
  3. With the brake pedal pressed, place the gear selector in the REVERSE and back to the PARK positions.

Does the test lamp illuminate as expected?

Go to Step 5

Go to Step 6

5

Inspect for poor connections at the harness connector of the backup lamp relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 10

Go to Step 8

6

Inspect for poor connections at the harness connector of the body control module (BCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 10

Go to Step 9

7

Repair a short to ground in the backup lamp supply voltage circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 10

--

8

Replace the backup lamp relay. Refer to Relay Replacement in Wiring Systems.

Did you complete the replacement?

Go to Step 10

--

9

Important: Perform the setup procedure for the BCM. Refer to Body Control Module (BCM) Programming/RPO Configuration in Body Control System.

Replace the BCM. Refer to Body Control Module Replacement in Body Control System.

Did you complete the replacement?

Go to Step 10

--

10

  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