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Home >> Buick >> 2017 >> Cascada Base >> Repair and Diagnosis >> Body & Frame >> Mirrors >> Mirror System >> Diagnostic Information and Procedures >> Power Mirror Malfunction >> Circuit/System Testing

Circuit/System Testing

Both Outside Rearview Mirrors Inoperative

  1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the S52 Outside Rearview Mirror Switch. It may take up to 2 minutes for all vehicle systems to power down.
  2. Test for less than 10 Ω between the ground circuit terminal 5 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.
    • Go to next step: If less than 10 Ω 
  3. Verify a test lamp illuminates between the B+ circuit terminal 4 and ground.
    • If the test lamp does not illuminate and the circuit fuse is good 
    1. Ignition OFF.
    2. Test for less than 2 Ω in the B+ circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, 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.
    2. Test for infinite resistance between the B+ circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • Go to next step: If infinite resistance
    3. Test for infinite resistance between each of the control circuit terminals listed below and ground:
      • Control circuit terminal 1
      • Control circuit terminal 2
      • Control circuit terminal 3
      • Control circuit terminal 7
      • Control circuit terminal 8
      • Control circuit terminal 9
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance, replace the appropriate M77 Outside Rearview Mirror Motor.
    • Go to next step: If the test lamp illuminates 
  4. Test or replace the S52 Outside Rearview Mirror Switch.

Driver Outside Mirror Movement Malfunction

  1. Ignition OFF, disconnect the harness connector at the A9A Outside Rearview Mirror-Driver. Ignition ON
  2. Connect a test lamp between the control circuit terminal 1 and control circuit terminal 2.
  3. Verify the test lamp turns ON when commanding the UP and DOWN states with the S52 Outside Rearview Mirror Switch.
    • If the test lamp remains OFF during either of the commands 
    1. Ignition OFF, remove the test lamp, disconnect the harness connector at the S52 Outside Rearview Mirror Switch.
    2. Test for infinite resistance between each control circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • Go to next step: If infinite resistance
    3. Test for less than 2 Ω in each control circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, test or replace the S52 Outside Rearview Mirror Switch.
    • If the test lamp is always ON 
    1. Ignition OFF, remove the test lamp, disconnect the harness connector at the S52 Outside Rearview Mirror Switch, ignition ON.
    2. Test for less than 1 V between each control circuit and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, test or replace the S52 Outside Rearview Mirror Switch
    • Go to next step: If the test lamp turns ON during each of the commands 
  4. Connect a test lamp between the control circuit terminal 1 and control circuit terminal 3.
  5. Verify the test lamp turns ON when commanding the LEFT and RIGHT states with the S52 Outside Rearview Mirror Switch.
    • If the test lamp remains OFF during either of the commands 
    1. Ignition OFF, remove the test lamp, disconnect the harness connector at the S52 Outside Rearview Mirror Switch.
    2. Test for infinite resistance between each control circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • Go to next step: If infinite resistance
    3. Test for less than 2 Ω in each control circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, test or replace the S52 Outside Rearview Mirror Switch.
    • If the test lamp is always ON 
    1. Ignition OFF, remove the test lamp, disconnect the harness connector at the S52 Outside Rearview Mirror Switch, ignition ON.
    2. Test for less than 1 V between each control circuit and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, test or replace the S52 Outside Rearview Mirror Switch
    • Go to next step: If the test lamp turns ON during each of the commands 
  6. Test or replace the M77D Outside Rearview Mirror Motor-Driver.

Passenger Outside Mirror Movement Malfunction

  1. Ignition OFF, disconnect the harness connector at the A9B Outside Rearview Mirror-Passenger. Ignition ON
  2. Connect a test lamp between the control circuit terminal 1 and control circuit terminal 2.
  3. Verify the test lamp turns ON when commanding the UP and DOWN states with the S52 Outside Rearview Mirror Switch.
    • If the test lamp remains OFF during either of the commands 
    1. Ignition OFF, remove the test lamp, disconnect the harness connector at the S52 Outside Rearview Mirror Switch.
    2. Test for infinite resistance between each control circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • Go to next step: If infinite resistance
    3. Test for less than 2 Ω in each control circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, test or replace the S52 Outside Rearview Mirror Switch.
    • If the test lamp is always ON 
    1. Ignition OFF, remove the test lamp, disconnect the harness connector at the S52 Outside Rearview Mirror Switch, ignition ON.
    2. Test for less than 1 V between each control circuit and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, test or replace the S52 Outside Rearview Mirror Switch
    • Go to next step: If the test lamp turns ON during each of the commands 
  4. Connect a test lamp between the control circuit terminal 1 and control circuit terminal 3.
  5. Verify the test lamp turns ON when commanding the LEFT and RIGHT states with the S52 Outside Rearview Mirror Switch.
    • If the test lamp remains OFF during either of the commands 
    1. Ignition OFF, remove the test lamp, disconnect the harness connector at the S52 Outside Rearview Mirror Switch.
    2. Test for infinite resistance between each control circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • Go to next step: If infinite resistance
    3. Test for less than 2 Ω in each control circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, test or replace the S52 Outside Rearview Mirror Switch.
    • If the test lamp is always ON 
    1. Ignition OFF, remove the test lamp, disconnect the harness connector at the S52 Outside Rearview Mirror Switch, ignition ON.
    2. Test for less than 1 V between each control circuit and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, test or replace the S52 Outside Rearview Mirror Switch
    • Go to next step: If the test lamp turns ON during each of the commands 
  6. Test or replace the M77P Outside Rearview Mirror Motor-Passenger.
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