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Home >> Cadillac >> 2021 >> CT4 Sport, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 191 (Data Communications - Diagnostic Information And Procedures (3 Of 3)) >> Diagnostic Information and Procedures >> Scan Tool Does Not Communicate with Device on CAN 2 >> Circuit/System Verification

Circuit/System Verification

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 ON/Vehicle In Service Mode.
  2. Verify that the scan tool is communicating with vehicle.
    • Go to next step: If the scan tool is communicating with vehicle 
  3. Attempt to communicate with all devices on the CAN 2 bus. Refer to Data Link References  to determine how many devices should be communicating on the CAN 2 bus.
  4. Verify two or more devices are not communicating on the CAN 2 bus.
    • If only one device is not communicating 

      Refer to Circuit/System Testing - Testing the Device Circuits  .

    • Go to next step: If two or more devices are not communicating 
  5. Refer to Circuit/System Testing - Serial Data Starting Point  .
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