Diagnostic Test

ACTIVE DTC 

1. Ignition on, engine not running.
2. With the scan tool, select view DTCs.

   Is the DTC Active at this time?

   Yes 

   • Perform the U0100-Lost Communication with ECM/PCM diagnostic procedure. Refer to the DTC INDEX article.

   No 

   • Perform the Stored Lost Communication DTCs diagnostic procedure. Refer to STORED LOST COMMUNICATION DTCS .