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Home >> Cadillac >> 2021 >> CT4 Sport, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 86 (Image Display Cameras) >> Diagnostic Information and Procedures >> DTC B1236 (UVB, DTC set in Radio) >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2022 Cadillac CT4. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition/Vehicle & All vehicle systems - Off
  2. Disconnect the electrical connector: X2 @ A11 Radio
  3. Apply the parking brake.
  4. Engine Running & Transmission in Reverse
  5. Verify a test lamp turns On between the test points: Control circuit terminal 13 & Ground
    • If the test lamp does not turn On 
    1. Ignition/Vehicle - Off & Remove - Test lamp
    2. Test for less than 2 ohms between the test points: Control circuit terminal 13 @ Component harness & The other end of the circuit
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • Go to next step: If less than 2 ohms
    3. Test for infinite resistance between the test points: Control circuit terminal 13 & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • If infinite resistance - Test or replace the component: K219 Exterior Lighting Control Module
    • Go to next step: If the test lamp turns On 
  6. Ignition/Vehicle & All vehicle systems - Off
  7. Disconnect the electrical connector: X5 @ A11 Radio
    8. NOTE:

    Before testing the coax cable, check the cable's exterior for being pinched, cut, damaged, or having loose connections at the components, all of which can cause reception issues.

  8. Disconnect electrical connector at B87 Rearview Camera
  9. Locate the appropriate pinout adapter and load test loop adapter from EL-52552 COAX FAKRA Cable Adaptor Kit.
  10. Connect the 2 adapters together, measure and record the resistance between the terminals at the pinout adapter.
  11. Disconnect the 2 adapters and connect each one to the appropriate end of the coax cable.
  12. At the pinout adapter test terminals, measure the total resistance of the coax cable loop including the connected load test adapter.
    • If not within 5 Ω of the reading from step 10. 

      Replace the coax cable

    • Go to next step: If within 5 Ω of the reading from step 10. 
  13. Replace the component: B87 Rearview Camera
  14. Apply the parking brake.
  15. Engine Running Transmission in Reverse
  16. Verify the repair corrected the DTC/symptom.
    • If a DTC or symptom exists 

      Replace the component: B87 Rearview Camera

    • Go to next step: If no DTC or symptom exists 
  17. All OK.
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