Vehicle Speed

Vehicle Speed:

A signal containing current vehicle speed information is obtained from pin 2 of the speedometer and applied to pin 39 of the ECM.

On cars with TCS the same information is also applied to pin 10 of the ETS control module.

The signal is in the form of a square wave and typical voltage varies between 0 and about 12 V. Vehicle speed information is transmitted as variations in the signal frequency.

Idle speed control is a function which is dependent on the signal from the vehicle speed sensor, as is the ability of the ECM to limit vehicle speed to 240 km/h.