This Preliminary Information communication provides information to the technician about vehicles that the cruise control being inoperative. Technician may find Diagnostic Trouble Code B3894 set in the Trailer Brake Control Module. Technician should follow published Service Information diagnostics first. Technician should check the "Master Cylinder Pressure" sensor parameter listed in the Trailer Brake Control Module data list. If it is displaying pressure with no brake pedal input, suspect a concern with the Master Cylinder Pressure Sensor, wiring/terminals, or Electronic Brake Control Module.
