GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

Schematic Reference: Exterior Lights Schematics

1

Did you perform the Lighting System Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Lighting Systems

2

  1. Turn ON the ignition, with the engine OFF.
  2. Apply the park brake.
  3. Place the gear selector in the REVERSE position.

Do both backup lamps illuminate?

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

3

Is only one lamp inoperative?

Go to Step 4

Go to Step 5

4

  1. Disconnect the inoperative backup lamp connector.
  2. Probe the backup lamp supply voltage circuit of the backup lamp connector with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

Go to Step 8

Go to Step 9

5

  1. Turn OFF the ignition.
  2. Disconnect the park neutral position switch connector on automatic transmissions or the backup lamp switch on manual transmissions.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the backup lamp supply voltage circuit of the connector with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

Go to Step 6

Go to Step 10

6

  1. Turn OFF the ignition.
  2. Connect a 15 amp fused jumper wire between the ignition positive voltage circuit of the appropriate switch and the backup lamp supply voltage circuit of the appropriate switch.
  3. Turn ON the ignition, with the engine OFF.

Do the backup lamps illuminate?

Go to Step 7

Go to Step 11

7

Inspect for poor connections at the harness connector of the appropriate 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 13

Go to Step 12

8

Repair an open or high resistance in the ground circuit of the inoperative backup lamp. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 13

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9

Repair an open or high resistance in the backup lamp supply voltage circuit of the inoperative backup lamp. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 13

--

10

Repair an open, high resistance, or short to ground in the ignition positive voltage circuit of the appropriate switch. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 13

--

11

Repair an open or high resistance in the backup lamp supply voltage circuit between the appropriate switch and the backup lamps. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 13

--

12

Replace the appropriate switch. Refer to Park/Neutral Position Switch Replacement in Automatic Transmission or Backup Lamp Switch Replacement in Manual Transmission.

Did you complete the replacement?

Go to Step 13

--

13

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3