This Preliminary Information communication provides information to the technician about vehicles that have Trailer connection not recognized or “Check Trailer wiring” or “Service Trailer Brake” message. Technician may find Diagnostic Trouble Codes C1112, C1113, C1114, C111B, U1556, and/or U1505. Technician will need to inspect the battery and Trailer Brake Power Module connector for corroded terminals and replace as necessary.
