For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle

• | Review Strategy Based Diagnosis

• | Diagnostic Procedure Instructions

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Reverse Gear Signal | 2 | 1 | 1 | C0010 5A
1. Reverse gear lamp inoperative 2. Reverse gear lamp always ON

### Circuit/System Description

When the transmission is placed in the reverse position, the engine control module (ECM) sends a serial data message to the body control module (BCM). The message indicates that the gear selector is in the reverse position. The BCM applies battery voltage to the backup lamps. The backup lamps are permanently grounded. Once the driver moves the gear selector out of the reverse position, a message is sent by the ECM via serial data requesting the BCM to remove battery voltage from the backup lamp control circuit.

### Reference Information

#### Schematic Reference

Exterior Lights Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Exterior Lighting Systems Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Control Module References

### Circuit/System Verification

Ignition ON, perform the Backup Lamps Relay Command test. The backup lamp should be ON/OFF

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the B16 Backup Lamp Switch.
2. Test for less than 5 Ω between the ground circuit harness connector terminal 2 and ground.

⇒ | If greater than the specified value, test the ground circuit for an open/high resistance.

3. Disconnect the X2 harness connector at the K20 Engine Control Module (ECM)
4. ignition On, test for less than 0.3 V at the B16 Backup Lamp Switch signal circuit harness connector terminal 1 and ground.

⇒ | If greater then the specified value, test the signal circuit for a short to voltage.

5. Ignition OFF, test for infinite resistance between the B16 Backup Lamp Switch signal circuit harness connector terminal 1and ground.

⇒ | If lower then the specified value, test the signal circuit for a short to ground.

6. Connect the harness connector at the B16 Backup Lamp Switch.
7. Reversing gear engaged, test for less than 5 Ω between the K20 Engine Control Module (ECM) X2 harness connector terminal listed below and ground:

• | Terminal 34 with LBY

• | Terminal 75 with LCD, LBX or LBS

• | Terminal 28 with LDE or 2H0

• | Terminal 18 with LDK or LBW

• | Terminal 82 with LLU

⇒ | If greater then the specified value, test the signal circuit for an open/high resistance. If the circuit test normal, test or replace the B16 Backup Lamp Switch.

8. Reversing gear disengaged, test for infinite resistance between the K20 Engine Control Module (ECM) X2 harness connector terminal listed below and ground:

• | Terminal 34 with LBY

• | Terminal 75 with LCD, LBX or LBS

• | Terminal 28 with LDE or 2H0

• | Terminal 18 with LDK or LBW

• | Terminal 82 with LLU

⇒ | If lower then the specified value, test or replace the B16 Backup Lamp Switch.

9. If all the circuits test normal, replace the K20 Engine Control Module (ECM).

### Component Testing

#### Static Test

1. Ignition OFF, disconnect the harness connector at the B16 Backup Lamp Switch. Reversing gear engaged, test for less than 5 Ω at the B16 Backup Lamp Switch terminal 1 and terminal 2.

⇒ | If greater than the specified value replace the B16 Backup Lamp Switch.

2. Reversing gear disengaged, test for infinite resistance at the B16 Backup Lamp Switch terminal 1 and terminal 2.

⇒ | If less than the specified value replace the B16 Backup Lamp Switch.

### Repair Instructions

Perform the Diagnostic Repair Verification

• | Tail Lamp Replacement

• | Backup Lamp Switch Replacement

• | Backup Lamp Switch Replacement

• | Control Module References