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Home >> Cadillac >> 2018 >> CT6 Plug-In >> Repair and Diagnosis >> Accessories & Equipment >> Drivers Assistance Systems - ADAS >> Image Display Camera Systems >> Diagnostic Information and Procedures >> Rear Vision Camera System Malfunction (without UVH, Z49, EF7, or CV4) >> Circuit/System Testing
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Circuit/System Testing

  1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the B87 Rearview Camera. It may take up to 2 min 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. Ignition ON.
  4. Verify a test lamp illuminates between the ignition circuit terminal 6 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 ignition circuit end to end.
    • If the test lamp does not illuminate and the circuit fuse is open 
    1. Ignition OFF.
    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, replace the B87 Rearview Camera.
    • Go to next step: If the test lamp illuminates 
  5. Engine running, parking brake applied, transmission in REVERSE.
  6. Verify a test lamp illuminates between the control circuit terminal 3 and ground.
    • If the test lamp does not illuminate 
    1. Ignition OFF, disconnect the X4 harness connector at the X50A Fuse Block - Underhood
    2. Test for less than 2 Ω in the ignition circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, refer to Backup Lamps Malfunction .
    • Go to next step: If the test lamp illuminates 
  7. Ignition OFF, disconnect the K74 Human Machine Interface Control Module X1 harness connector. Ignition ON.
  8. Verify a test lamp illuminates between serial data communication enable circuit terminal 5 and ground.
    • If the test lamp does not illuminate 
    1. Ignition/Vehicle OFF.
    2. Test for infinite resistance between the serial data communication enable 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 the serial data communication enable circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the control module that controls the serial data communication enable circuit.
    • Go to next step: If the test lamp illuminates 
  9. Ignition OFF, Connect the K74 Human Machine Interface Control Module X1 harness connector.
  10. Disconnect the X2 harness connector at the K74 Human Machine Interface Control Module, ignition ON.
  11. Test for less than 1 V between the signal circuit terminals listed below and ground:
    • K74 Human Machine Interface Control Module signal (+) circuit terminal 5 X2
    • K74 Human Machine Interface Control Module signal (-) circuit terminal 6 X2
    • If 1 V or greater 

      Repair the short to voltage on the circuit.

    • Go to next step: If less than 1 V 
  12. Test for infinite resistance between the signal circuit terminals listed below and ground:
    • K74 Human Machine Interface Control Module signal (+) circuit terminal 5 X2
    • K74 Human Machine Interface Control Module signal (-) circuit terminal 6 X2
    • If less than infinite resistance 

      Repair the short to ground on the circuit.

    • Go to next step: If infinite resistance 
  13. Test for less than 2 Ω between the K74 Human Machine Interface Control Module signal (+) circuit terminal 5 X2 and the B87 Rearview Camera signal (+) circuit terminal 1.
    • If 2 Ω or greater 

      Repair the open/high resistance in the circuit.

    • Go to next step: If less than 2 Ω 
  14. Test for less than 2 Ω between the K74 Human Machine Interface Control Module signal (+) circuit terminal 6 X2 and the B87 Rearview Camera signal (+) circuit terminal 4.
    • If 2 Ω or greater 

      Test the signal circuit for an open/high resistance.

    • Go to next step: If less than 2 Ω 
  15. Replace the B87 Rearview Camera.
  16. Engine running, parking brake applied, transmission in REVERSE.
  17. Verify a clear rear vision image is displayed on the P17 Info Display Module.
    • If a clear rear vision image is not displayed 

      Replace the K74 Human Machine Interface Control Module.

    • Go to next step: If a clear rear vision image is displayed 
  18. All OK.
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