Faulty Vehicle Speed Sensor
Vehicle speed sensor harness or connectors is open or shorted
Vehicle speed sensor circuit poor electrical connection
Faulty Engine Control Module (ECM)
Engine Light ON (or Service Engine Soon Warning Light)
Speedometer may not work properly
Transmission shifting problem
The vehicle speed sensor outputs a 4 pulse signal for every revolution of the rotor shaft, which is rotated by the transmission output shaft via the driven gear. After this signal is converted into a more precise rectangular waveform by the waveform shaping circuit inside the combination meter, it is then transmitted to the Engine Control Module (ECM). The ECM determines the vehicle speed based on the frequency of these pulse signals.