Vehicle Speed Sensor: Description and Operation

Vehicle speed sensor circuit description

Vehicle Speed Sensor NO.1







This sensor is mounted in the combination meter. It contains a magnet which is rotated by the speed meter cable.
Turning the reed switch ON and OFF 4 times for every revolution of the speedmeter. It is then trtansmitted to the ECM. The ECM determines the vehicle speed based on thr frequency ot these pulse signals.


Vehicle Speed Sensor NO.2

Speed Sensor NO.2:

The No.2 vehicle speed sensor detects the rotation speed of the transmission output shaft and sends signals to the ECM. The ECM determines the vehicle speed based on these signals.
An AC voltage is generated in the No.2 vehicle speed sensor coil as the rotor mounted on the output shaft rotates, and this voltage is sent to the ECM.
The gear shift point and lock-up timing are controlled by the ECM based on the signals from this vehicle speed sensor and the throttle position sensor signal.
If the No.2 vehicle speed sensor malfunctions, the ECM uses input signals from the No.1 vehicle speed sensor as a back-up signal.