Vehicle Speed Sensor (VSS)

The VSS pulses ECM signal to ground when vehicle is in motion. VSS uses a ground circuit, a 12-volt supply to power the Hall effect switch circuit, and a 12-volt signal circuit from the ECM. The pulse rate is 3683 times per mile. The ECM calculates vehicle speed by measuring the time between pulses. This information is used for idle speed and torque converter clutch control.