DTC P0501: VEHICLE SPEED SIGNAL RATIONALITY Monitor & Set Conditions Vehicle Speed Sensor (VSS) signal is monitored when no VSS DTCs or Chrysler Collision Detection (CCD) errors are set. DTC may be stored when CCD vehicle speed indicates greater than 20 MPH for 2 seconds, ECM vehicle speed indicates less than 10 MPH and PCM does not receive a VSS signal from Controller Anti-Lock Brake (CAB) module.