GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

Schematic Reference: Exterior Lights Schematics

1

Did you perform the Lighting Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Lighting Systems

2

Operate the backup lamps to verify the fault is present.

Does the system operate normally?

Go to Testing for Electrical Intermittents in Wiring Systems

Go to Step 3

3

  1. Turn the ON the ignition, with the engine OFF.
  2. Set the park brake.
  3. Place the transmission in the neutral position.
  4. Disconnect the back-up lamp switch.

Are the back-up lamps on?

Go to Step 4

Go to Step 5

4

Remove the VEH B/U fuse.

Are the back-up lamps on?

Go to Step 6

Go to Step 7

5

Inspect for poor connections at the harness connector of the backup lamp switch or park/neutral position switch. 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 9

Go to Step 8

6

Repair the backup lamp supply voltage circuit for a short to voltage between the engine wiring harness junction block and the back-up lamps. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 9

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7

Repair the backup lamp supply voltage circuit for a short to voltage between the engine wiring harness junction block and the back-up lamp switch. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 9

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8

Replace the backup lamp switch or park/neutral position switch. Refer to the following:

    •  Park/Neutral Position Switch Replacement in Automatic Transmission - 4L60-E
    •  Park/Neutral Position Switch Adjustment in Automatic Transmission - 4L80-E
    •  Park/Neutral Position Switch Replacement in Automatic Transmission - Allison
    •  Backup Lamp Switch Replacement in Manual Transmission - NV 3500
    •  Backup Lamp Switch Replacement in Manual Transmission - NV 4500
    •  Backup Lamp Switch Replacement in Manual Transmission - ZF S6-650

Did you complete the repair?

Go to Step 9

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9

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3