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Home >> Infiniti >> 2012 >> M37 Base >> Repair and Diagnosis >> Transmission >> Automatic Transmission >> DTC/Circuit Diagnosis >> DTC P1721: Vehicle Speed Signal >> DTC Logic >> DTC Detection Logic

DTC Detection Logic

DTC Trouble diagnosis name DTC is detected if... Possible cause
P1721 Vehicle Speed Signal Circuit
  • The vehicle speed transmitted from the combination meter to TCM is 5 km/h (3 MPH) or less when the vehicle speed detected by the output speed sensor is 20 km/h (12 MPH) or more. (Only when starts after the ignition switch is turned ON.)
  • The vehicle speed detected by the output speed sensor does not decrease despite the 36 km/h (23 MPH) or more of deceleration in vehicle speed received from the combination meter when the vehicle speed transmitted from the combination meter to TCM is 36 km/h (23 MPH) or more and the vehicle speed detected by the output speed sensor is 24 km/h (15 MPH) or more.
Harness or connectors (Sensor circuit is open or shorted.)