GM Service Manual Online
For 1990-2009 cars only

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 Lighting System Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Lighting Systems

2

  1. Turn the ignition ON.
  2. Apply the park brake.
  3. Shift the gear selector lever to the REVERSE position.

Do the both backup lamps turn on?

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

Go to Step 3

3

Is only one backup lamp inoperative?

Go to Step 7

Go to Step 4

4

    • Install a scan tool.
    • Turn ON the ignition , with the engine OFF.
    • With a scan tool, command the backup lamp relay ON.

Do the backup lamps illuminate when commanded by the Body Control Module (BCM)?

Go to Step 11

Go to Step 5

5

  1. Turn the ignition to the OFF position.
  2. Disconnect the backup lamp relay.
  3. Turn the ignition to the ON position.
  4. Connect a test lamp to ground and probe the switch side battery positive voltage for the backup lamp relay.

Does the test lamp illuminate?

Go to Step 6

Go to Step 13

6

Install a fused jumper across the switch side battery positive voltage supply circuit of the backup lamp relay and the backup lamp supply voltage circuit of the backup lamp relay.

Do the backup lamps turn on?

Go to Step 12

Go to Step 9

7

  1. Disconnect the inoperative backup lamp.
  2. Connect a test lamp between the backup lamps supply voltage circuit of the inoperative backup lamp and a ground.

Does the test lamp illuminate?

Go to Step 8

Go to Step 14

8

Connect a test lamp between the ground circuit and supply voltage circuit of the inoperative backup lamp.

Does the test lamp illuminate?

Go to Step 10

Go to Step 15

9

Test for a high resistance or an open in the backup lamps supply voltage circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 20

Go to Step 16

10

Inspect for poor connections at the harness connector of the inoperative backup lamp. 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 20

Go to Step 17

11

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 20

Go to Step 18

12

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 20

Go to Step 19

13

Repair a high resistance or an open in the switch side battery positive voltage supply circuit of the backup lamp relay . Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 20

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14

Repair a high resistance or an open 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 20

--

15

Repair a high resistance or an open in the backup lamp 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 20

--

16

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

Did you complete the repair?

Go to Step 20

--

17

Replace the inoperative backup lamp. Refer to Tail Lamp Assembly and /or Backup, Sidemarker, Stop, Turn Signal Bulb Replacement .

Did you complete the repair?

Go to Step 20

--

18

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

Replace the BCM.

Did you complete the repair?

Go to Step 20

--

19

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

Did you complete the repair?

Go to Step 20

--

20

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2