When the PRNDL is placed in the REVERSE position, a serial data message is sent from the transmission control module (TCM) to the body control module (BCM). The BCM responds by applying battery voltage through the backup lamps control circuit to the tail lamp assemblies illuminating the backup lamps.

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

Scan Tool Reference

Control Module References for scan tool information

1. Ignition OFF, disconnect the harness connector at the appropriate tail lamp assembly.
2. Ignition OFF, exterior lamps OFF, test for less than 5 ohms between the ground circuit terminal 3 and ground.

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

3. Connect a test lamp between the control circuit terminal 1 and ground.
4. Command the Backup Lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

⇒	If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM.

⇒	If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.

5. If all circuits test normal, test or replace the inoperative tail lamp.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.