Circuit/System Testing

WARNING: This page is about a different car, the 2013 Buick Regal. However, it is still accessible from the selected car via links, so may be relevant.

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 10 Ω between the ground circuit terminal A X2 and ground.
- If 10 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.
- If less than 10 Ω
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 1 V between the control circuit and ground.
  - If 1 V or greater, repair the short to voltage on the circuit.
  - If less than 1 V, 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 2 Ω in the control circuit end to end.
  - If 2 Ω or greater, repair the open/high resistance in the circuit.
  - If less than 2 Ω refer to Rear Window Defogger Malfunction .
- If the lamp turns on and off
Replace the E17 Outside Rearview Mirror Glass.