Circuit/System Testing

Ignition OFF and all vehicle systems OFF, disconnect the X1 and X2 harness connector at the appropriate E17 Outside Rearview Mirror Glass. It may take up to 2 minutes for all vehicle systems to power down.
Test for less than 10Ω between the ground circuit terminal A X2 and ground.
- If 10Ω or greater
1. Ignition OFF.
2. Test for less than 2Ω in the ground circuit end to end.
  - If 2Ω or greater, repair the open/high resistance in the circuit.
  - If less than 2Ω, repair the open/high resistance in the ground connection.
- If less than 10Ω
Connect a test lamp between the control circuit terminal A X1 and ground.
Engine running.
Verify the test lamp turns ON and OFF when commanding the Rear Defogger On and Off with a scan tool.
- If the lamp is always ON
1. Ignition OFF, disconnect the X2 harness connector at X50A Fuse Block - Underhood, ignition ON.
2. Test for less than 1V between the control circuit and ground.
  - If 1V or greater, repair the short to voltage on the circuit.
  - If less than 1V, refer to Rear Window Defogger Malfunction .
- If the lamp is always OFF
1. Ignition OFF, disconnect the harness connector at X50A Fuse Block - Underhood, ignition ON.
2. Test for infinite resistance between the control circuit and ground.
  - If less than infinite resistance, repair the short to ground on the circuit.
  - If infinite resistance
3. Test for less than 2Ω in the control circuit end to end.
  - If 2Ω or greater, repair the open/high resistance in the circuit.
  - If less than 2Ω refer to Rear Window Defogger Malfunction .
- If the lamp turns on and off
Replace the E17 Outside Rearview Mirror Glass.