Circuit Description

Wheel speed sensors on each wheel deliver an input signal to Vehicle Skid Control (VSC) Electronic Control Unit (ECU). VSC ECU converts input signals from wheel speed sensors to a 4-pulse input signal to the instrument cluster. Instrument cluster then converts 4-pulse input signal to a rectangular waveform and then sends vehicle speed signal to ECM. ECM determines vehicle speed by using input signal. DTC is set if there is no vehicle speed signal to ECM while vehicle is being driven. Possible causes are:

• Vehicle speed circuit is open or shorted between instrument cluster and ECM.
• Defective instrument cluster.
• Defective ECM.