Backup Lamps Malfunction (MT)
Backup Lamps Malfunction (MT)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.
Diagnostic Fault Information
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 (Exterior Lights Schematics)
Connector End View Reference
Component Connector End Views (Connector End Views By Name)
Description and Operation
Exterior Lighting Systems Description and Operation (Exterior Lighting Systems)
Electrical Information Reference
* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)
Scan Tool Reference
Control Module References (Programming and Relearning)
Circuit/System Verification
Ignition ON, perform the Backup Lamps Relay 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 ohm between the ground circuit harness connector terminal B 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.
4. ignition ON, test for less than 0.3 V at the B16 Backup Lamp Switch signal circuit harness connector terminal A 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 A and 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 8 ohm between the K20 Engine Control Module X2 harness connector terminal 87 and ground.
• 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 X2 harness connector terminal 87 and ground.
• 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.
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 ohm at the B16 Backup Lamp Switch terminal A and terminal B.
• 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 A and terminal B.
• If less than the specified value replace the B16 Backup Lamp Switch.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests)
* Tail Lamp Replacement (Service and Repair)
* Control Module References (Programming and Relearning)