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Home >> Cadillac >> 2021 >> CT4 Sport, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 228 (Vehicle Access System - Diagnostic Information And Procedures) >> Diagnostic Information and Procedures >> DTC B15EC or B15ED >> 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.

Test 1

  1. Ignition/vehicle OFF, disconnect the connector at the B27LR Rear Side Door Outside Handle Switch - Left. Ignition ON
  2. Verify the scan tool Left Rear Door Exterior Lock/Unlock Switch Status parameter is Inactive
    • If not Inactive 
    1. Test the circuit 4991 for a short to ground
      • If a short to ground is found, repair the fault on the circuit.
      • Go to next step: If a short to ground is not found.
    2. Replace the K9 Body Control Module.
    • Go to next step: If Inactive 
  3. Install a 3 A fused jumper wire between the signal circuit terminal 1 and ground.
  4. Verify the scan tool parameter is now Active.
    • If not Active and the 3 A fuse is OK 
    1. Test the circuit 4991 for an open/high resistance.
      • If an open/high resistance is found, repair the fault on the circuit.
      • Go to next step: If an open/high resistance is not found.
    2. Replace the K9 Body Control Module.
    • If not Active and the 3 A fuse is open 
    1. Test the circuit 4991 for a short to voltage.
      • If a short to voltage is found, repair the fault on the circuit.
      • Go to next step: If a short to voltage is not found.
    2. Replace the K9 Body Control Module.
    • Go to next step: If Active 
  5. Replace the B27LR Rear Side Door Outside Handle Switch - Left

Test 2

  1. Ignition/vehicle OFF, disconnect the connector at the A23RR Rear Side Door Outside Handle Switch - Right. Ignition ON
  2. Verify the scan tool Right Rear Door Exterior Lock/Unlock Switch Status parameter is Inactive
    • If not Inactive 
    1. Test the circuit 4992 for a short to ground
      • If a short to ground is found, repair the fault on the circuit.
      • Go to next step: If a short to ground is not found.
    2. Replace the K9 Body Control Module.
    • Go to next step: If Inactive 
  3. Install a 3 A fused jumper wire between the signal circuit terminal 1 and ground.
  4. Verify the scan tool parameter is now Active.
    • If not Active and the 3 A fuse is OK 
    1. Test the circuit 4992 for an open/high resistance.
      • If an open/high resistance is found, repair the fault on the circuit.
      • Go to next step: If an open/high resistance is not found.
    2. Replace the K9 Body Control Module.
    • If not Active and the 3 A fuse is open 
    1. Test the circuit 4992 for a short to voltage.
      • If a short to voltage is found, repair the fault on the circuit.
      • Go to next step: If a short to voltage is not found.
    2. Replace the K9 Body Control Module.
    • Go to next step: If Active 
  5. Replace the A23RR Rear Side Door Outside Handle Switch - Right
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