Circuit Description

The vehicle speed information is provided to the engine control module (ECM) by the vehicle speed sensor (VSS). The VSS is a permanent magnet generator that is mounted to the transmission and produces a pulsing voltage. The AC voltage amplitude and frequency increases with vehicle speed. The ECM converts the pulsing voltage into km/h (mph). The VSS signal is also supplied to the following components:

• The instrument panel for speedometer and odometer operation
• The clock
• The HVAC control module

If the ECM detects no vehicle speed for a calibrated amount of time, this DTC sets.