For 1990-2009 cars

## Backup Lamps Inoperative RPO MWF

Step | Action | Yes | No
--- | --- | --- | ---
Schematic Reference: Exterior Lights Schematics
1 | Did you review the backup lamps operation and perform the necessary inspections? | Go to Step 2 | Go to Symptoms - Lighting Systems
2 |

1. Block the wheels or set the parking brake.
2. Place the transmission in reverse.
3. Turn ON the ignition, with the engine OFF.

Are the backup lamps illuminated?

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

Go to Step 3

3 |

1. Turn OFF the ignition.
2. Disconnect the reverse warning relay.
3. Turn ON the ignition, with the engine OFF.
4. Probe the reverse warning relay switch side voltage supply circuit with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

Go to Step 4

Go to Step 9

4 |

1. Turn OFF the ignition.
2. Connect a fused jumper wire between the reverse warning relay switch side voltage supply circuit and the switch side output circuit.
3. Turn ON the ignition, with the engine OFF.

Do the backup lamps illuminate?

Go to Step 7

Go to Step 6

5 | Does the fuse in the jumper wire open? | Go to Step 10 | Go to Step 6
6 | Leave the fused jumper wire connected. Probe the backup lamps voltage supply circuit at the right or left backup lamp with a test lamp that is connected to a good ground. Does the test lamp illuminate? | Go to Step 11 | Go to Step 12
7 | Test the reverse warning relay control circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 14 | Go to Step 8
8 | Inspect for poor connections at the reverse warning 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 14 | Go to Step 13
9 | Repair an open, high resistance, or short to ground in the reverse warning relay switch side voltage supply circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 14 | --
10 | Repair a short to ground on the backup lamps voltage supply circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 14 | --
11 | Repair an open or high resistance in the backup lamps ground circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 14 | --
12 | Repair an open or high resistance in the backup lamps voltage supply circuit. Refer to Circuit Testing and Wiring Repairs in wiring systems. Did you complete the repair? | Go to Step 14 | --
13 | Replace the reverse warning relay. Did you complete the replacement? | Go to Step 14 | --
14 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3

## Backup Lamps Inoperative Without RPO MWF

Step | Action | Yes | No
--- | --- | --- | ---
Schematic Reference: Exterior Lights Schematics
1 | Did you review the backup lamps operation and perform the necessary inspections? | Go to Step 2 | Go to Symptoms - Lighting Systems
2 |

1. Block the wheels or set the parking brake.
2. Turn ON the ignition, with the engine OFF.
3. Place the transmission in reverse.

Do the backup lamps illuminate?

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

Go to Step 3

3 | Disconnect the backup lamp switch or park/neutral position and backup lamp switch. Probe the backup lamp voltage input side of the appropriate switch connector with a test lamp that is connected to a good ground. Does the test lamp illuminate? | Go to Step 4 | Go to Step 8
4 |

1. Turn OFF the ignition.
2. Connect a fused jumper wire between the backup lamp voltage input and output sides of the appropriate switch connector.
3. Turn ON the ignition, with the engine OFF.

Do the backup lamps illuminate?

Go to Step 7

Go to Step 6

5 | Does the fuse in the jumper wire open? | Go to Step 9 | Go to Step 6
6 |

1. Leave the jumper wire connected
2. Disconnect one of the backup lamps.
3. Probe the voltage supply circuit of the disconnected backup lamp with a test lamp connected to a good ground.

Does the test lamp illuminate?

Go to Step 10

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, high resistance, or short to ground in the backup lamp voltage input circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 13 | --
9 | Repair a short to ground in the backup lamps voltage supply circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 13 | --
10 | Repair an open or high resistance in the backup lamp ground circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 13 | --
11 | Repair an open, high resistance, or short to ground in the backup lamps voltage supply circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 13 | --
12 | Replace the appropriate backup lamp switch. Refer to Park/Neutral Backup Switch Replacement in the Automatic Transmission section or Backup Lamp Switch Replacement in Manual Transmission - Medium Duty. 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