Circuit/System Testing

Ignition OFF, exterior lamps OFF, all doors closed, disconnect the harness connector at the B16 Backup Lamp Switch. It may take up to 2 min for all vehicle systems to power down.
Test for less than 5 Ω between the ground circuit terminal B and ground.
- If 5 Ω or greater
1. Ignition OFF.
2. Test for less than 2 Ω in the ground circuit end to end.
  - If 2 Ω or greater, repair the open/high resistance in the circuit.
  - If less than 2 Ω, repair the open/high resistance in the ground connection.
- Go to next step: If less than 5 Ω
Ignition ON.
Verify the scan tool Reverse Position Switch parameter is Off.
- If not Off
1. Ignition OFF, disconnect the appropriate harness connector listed below at the K20 Engine Control Module.
  - X2 - (with LGX)
  - X3 - (with LTG)
2. Test for infinite resistance between the signal circuit terminal A and ground.
  - If less than infinite resistance, repair the short to ground on the circuit.
  - If infinite resistance, replace the K20 Engine Control Module.
- Go to next step: If Off
Install a 3 A fused jumper wire between the signal circuit terminal A and ground.
Verify the scan tool Reverse Position Switch parameter is On.
- If not On
1. Ignition OFF, disconnect the appropriate harness connector listed below at the K20 Engine Control Module, ignition ON.
  - X2 - (with LGX)
  - X3 - (with LTG)
2. Test for less than 1 V between the signal circuit terminal A and ground.
  - If 1 V or greater, repair the short to voltage on the circuit.
  - Go to next step: If less than 1 V
3. Test for less than 2 Ω in the signal circuit end to end.
  - If 2 Ω or greater, repair the open/high resistance in the circuit.
  - If less than 2 Ω, replace the K20 Engine Control Module.
- Go to next step: If On
Test or replace the B16 Backup Lamp Switch.