Circuit/System Verification

Ignition ON/Vehicle In Service Mode.
Verify that the scan tool is communicating with vehicle.
- If the scan tool is not communicating with vehicle
  Refer to Scan Tool Does Not Communicate with Vehicle .
- Go to next step: If the scan tool is communicating with vehicle
Attempt to communicate with all devices on the Powertrain CAN bus. Refer to Data Link References to determine how many devices should be communicating on the Powertrain CAN bus.
Verify two or more devices are not communicating on the Powertrain CAN 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
Refer to Circuit/System Testing - Serial Data Starting Point .