GM Service Manual Online
For 1990-2009 cars only

Backup Lamps Always On Automatic Transmission

Test Description

The number below refers to the step number on the diagnostic table.

  1. Listen for an audible click when the reverse relay operates. Command both the ON and OFF states. Repeat the commands as necessary.

Step

Action

Yes

No

Schematic Reference: Exterior Lights Schematics

Connector End View Reference: Master Electrical Component List

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

  1. Turn ON the ignition, with the engine OFF.
  2. Depress and hold the brake pedal.
  3. Move the gear selector through the gear ranges.
  4. Observe the backup lamps.
  5. Place the gear selector in the PARK position.
  6. Release the brake pedal.

Did the backup lamps operate properly?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With the scan tool, command the Reverse Lamp Relay ON and OFF from the rear integration module (RIM) Output Control data list.

Does the reverse relay turn ON and OFF with each command?

Go to Step 4

Go to Step 5

4

  1. Turn OFF the ignition.
  2. Disconnect the reverse relay. Refer to Relay Replacement .
  3. Turn ON the ignition, with the engine OFF.

Do the backup lamps turn OFF?

Go to Step 5

Go to Step 7

5

  1. Turn OFF the ignition.
  2. Connect a test lamp between the reverse relay control side supply voltage circuit and the reverse lamp relay control circuit.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, command the Reverse Lamp Relay ON and OFF.

Does the test lamp turn ON and OFF with each command?

Go to Step 8

Go to Step 6

6

Test the reverse lamp relay control circuit for a short ground. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 12

Go to Step 9

7

Test the backup lamp supply voltage circuit for a short to battery positive voltage. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 12

Go to Step 8

8

Inspect for poor connections at the reverse lamp relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 12

Go to Step 10

9

Inspect for poor connections at the harness connector of the RIM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 12

Go to Step 11

10

Replace the reverse relay. Refer to Relay Replacement .

Did you complete the replacement?

Go to Step 12

--

11

Replace the RIM. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 12

--

12

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2

Backup Lamps Always On Manual Transmission

Test Description

The number below refers to the step number on the diagnostic table.

  1. Listen for an audible click when the reverse relay operates. Command both the ON and OFF states. Repeat the commands as necessary.

Step

Action

Yes

No

Schematic Reference: Exterior Lights Schematics

Connector End View Reference: Master Electrical Component List

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

  1. Turn ON the ignition, with the engine OFF.
  2. Depress and hold the brake pedal.
  3. Move the gear selector through the gear ranges.
  4. Observe the backup lamps.
  5. Place the gear selector in the park position.
  6. Release the brake pedal.

Did the backup lamps operate properly?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With the scan tool, command the reverse lamp relay ON and OFF from the rear integration module (RIM) Output Control data list.

Does the reverse relay turn ON and OFF with each command?

Go to Step 4

Go to Step 5

4

  1. Turn OFF the ignition.
  2. Disconnect the reverse relay. Refer to Relay Replacement .
  3. Turn ON the ignition, with the engine OFF.

Do the backup lamps turn OFF?

Go to Step 5

Go to Step 8

5

  1. Turn OFF the ignition.
  2. Connect a test lamp between the reverse relay control side supply voltage circuit and the reverse lamp relay control circuit.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, command the reverse lamp relay ON and OFF.

Does the test lamp turn ON and OFF with each command?

Go to Step 9

Go to Step 6

6

Test the reverse lamp relay control circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 13

Go to Step 7

7

Test the reverse switch signal circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 13

Go to Step 9

8

Test the backup lamp supply voltage circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 13

Go to Step 8

9

Inspect for poor connections at the reverse lamp relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 13

Go to Step 10

10

Inspect for poor connections at the harness connector of the RIM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 13

Go to Step 12

11

Replace the reverse relay. Refer to Relay Replacement .

Did you complete the replacement?

Go to Step 13

--

12

Replace the RIM. Refer to Control Module References for replacement, setup, and programming.

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 2