General Description

The vehicle speed sensor (VSS) mounts to the automatic or manual transmission assembly and uses a permanent magnet generator to produce an alternating current (AC) signal. The frequency of this signal is proportional to the speed at which the transmission output shaft rotates, which in turn is proportional to the speed of the vehicle.

The AC signal produced by the VSS is amplified and converted by the VSS calibrator. The signal is supplied to the PCM/VCM, cruise control module, and speedometer by the VSS calibrator. The VSS calibrator produces the signal by opening and closing internal solid-state switches to ground. The VSS calibrator is integral to the PCM/VCM and is not serviceable.

The signal to the PCM/VCM, cruise control module, and speedometer pulses at a rate of 4,000 times per mile. The PCM/VCM, cruise control module, and speedometer internally convert the number of pulses per mile to determine vehicle speed.