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Home >> Buick >> 2015 >> Regal GS, AWD >> Repair and Diagnosis >> Body & Frame >> Mirrors >> Mirror System >> Diagnostic Information and Procedures >> Automatic Day-Night Mirrors Malfunction >> Circuit/System Testing

Circuit/System Testing

Inside Review Mirror Dimming Inoperative

  1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the A10 Inside Rearview Mirror. It may take up to 2 minutes for all vehicle systems to power down.
  2. Test for less than 10Ω between the ground circuit terminal 5 and ground.
    • If 10Ω or greater 
    1. Ignition OFF, remove the test lamp.
    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 
  3. Ignition ON.
  4. Verify a test lamp illuminates between the ignition circuit terminal 2 and ground.
    • If the test lamp does not illuminate and the circuit fuse is good 
    1. Ignition OFF, remove the test lamp.
    2. Test for less than 2Ω in the ignition circuit end to end.
      • If 2Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2Ω, verify the fuse is not open and there is voltage at the fuse.
    • If the test lamp does not illuminate and the circuit fuse is open 
    1. Ignition OFF, remove the test lamp.
    2. Test for infinite resistance between the ignition circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance
    3. Test for infinite resistance between the signal circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance, replace the A10 Inside Rearview Mirror
    • If the test lamp illuminates 
  5. Replace the A10 Inside Rearview Mirror.

Day-Night Disable Malfunction

  1. Ignition OFF, disconnect the harness connector at the A10 Inside Rearview Mirror. Ignition ON
  2. Connect a test lamp between the control circuit terminal 1 and ground
  3. Verify the test lamp turns ON and OFF while commanding the Backup Lamps Active and Inactive with a scan tool.
    • If the test lamp is always OFF 
    1. Ignition OFF, remove the test lamp, disconnect the harness connector at the K9 Body Control Module.
    2. Test for infinite resistance between the control circuit terminal 1 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 the test lamp is always ON 
    1. Ignition OFF, remove the test lamp, disconnect the harness connector at the K9 Body Control Module, ignition ON.
    2. Test for less than 1V between the control circuit and ground.
    • If the test lamp turns ON and OFF 
  4. Replace the A10 Inside Rearview Mirror.

Outside Rearview Mirror Dimming Malfunction

  1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the A9A Outside Rearview Mirror-Driver. It may take up to 2 minutes for all vehicle systems to power down.
  2. Test for less than 10Ω between the low reference circuit terminal 16 and ground.
    • If 10Ω or greater 
    1. Ignition OFF, disconnect the harness connector at the A10 Inside Rearview Mirror.
    2. Test for less than 2Ω in the low reference circuit end to end.
      • If 2Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2Ω, replace the A10 Inside Rearview Mirror.
    • If less than 10Ω 
  3. Ignition ON.
  4. Test for less than 1V between the control circuit terminal 2 and ground.
    • If 1V or greater 
    1. Ignition OFF, disconnect the harness connector at the A10 Inside Rearview Mirror, 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 replace the A10 Inside Rearview Mirror.
    • If less than 1V  
  5. Ignition ON, headlamps ON, vehicle in PARK, cover the front light sensor with a towel or other suitable item. Shine a flashlight at the rear light sensor.
  6. Test for greater than 1V between the control circuit terminal 2 and ground.
    • If 1V or less 
    1. Ignition OFF, disconnect the harness connector at the A10 Inside Rearview Mirror, 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, test or replace the A10 Inside Rearview Mirror.
    • If greater than 1V 
  7. Test or replace A9A Outside Rearview Mirror-Driver.
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