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Home >> Cadillac >> 2017 >> Escalade ESV Base, 4WD >> Repair and Diagnosis >> Accessories & Equipment >> Collision/Avoidance >> Object Detection System And Pedestrian Protection System - Diagnostic Information And Procedures >> Diagnostic Information and Procedures >> DTC B127B: Rearview Camera Input Signal Circuit (with IO3) >> Circuit/System Testing
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Circuit/System Testing

  1. Ignition OFF and all vehicle systems OFF, disconnect the X900 harness connector. 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 7 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 
  3. Ignition ON.
  4. Verify a test lamp illuminates between the ignition 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 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.
    • If the test lamp illuminates 
  5. Engine running, park brake applied, transmission in R.
  6. Verify a test lamp illuminates between the control circuit terminal 2 and ground.
    • If the test lamp does not illuminate 
    1. Ignition OFF.
    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, verify the fuse is good and there is voltage at the fuse. Refer to Backup Lamps Malfunction .
    • If the test lamp illuminates 
  7. Ignition OFF, disconnect the X1 harness connector at the A11 Radio, ignition ON.
  8. Test for less than 1 V between the signal circuit terminals listed below and ground:
    • A11 Radio signal (+) circuit terminal 5 X1
    • A11 Radio signal (-) circuit terminal 4 X1
    • If 1 V or greater 

      Repair the short to voltage on the circuit.

    • If less than 1 V 
  9. Test for infinite resistance between the signal circuit terminals listed below and ground:
    • A11 Radio signal (+) circuit terminal 5 X1
    • A11 Radio signal (-) circuit terminal 4 X1
    • If less than infinite resistance 

      Repair the short to ground on the circuit.

    • If infinite resistance 
  10. Test for less than 2 Ω between the A11 Radio signal (+) circuit terminal 5 X1 and the X900 signal (+) circuit terminal 3.
    • If 2 Ω or greater 

      Repair the open/high resistance on the circuit.

    • If less than 2 Ω 
  11. Test for less than 2 Ω between the A11 Radio signal (-) circuit terminal 4 X1 and the X900 signal (-) circuit terminal 8.
    • If 2 Ω or greater 

      Repair the open/high resistance on the circuit.

    • If less than 2 Ω 
  12. Add Nyogel lubricant 760G to electrical terminals.
  13. Reconnect all electrical connections.
  14. Engine running, park brake applied, transmission in R.
  15. Verify a clear rear vision image is displayed on the P17 Info Display Module.
    • If a blank blue screen or distorted image is displayed 
    1. Replace the B87 Rearview Camera.
    2. Engine running, transmission in R,
    3. 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 A11 Radio.

      • If a clear rear vision image is displayed 
    4. All OK.
    • If a blank black screen is displayed 

      Replace the A11 Radio.

    • If a clear rear vision image is displayed 
  16. All OK.