April 5, 2026: LEMON Manuals is launched! Read the announcement.

Diagnostic Test

VERIFY THE DTC IS ACTIVE
1. Turn the ignition on.
2. With the scan tool, read active DTCs.
  Is the DTC active at this time?
  
  Yes
  - Refer to DIAGNOSIS AND TESTING and perform the U0121-00-Lost Communication with Anti-lock Brake System (ABS) Module diagnostic procedure.
  No
  - Refer to DIAGNOSIS AND TESTING and perform the Stored Lost Communication DTCs diagnostic procedure.