Vehicle Speed Sensor Signal: Description and Operation

DESCRIPTION
The vehicle speed sensor (VSS) is located on the transmission and is used to establish vehicle speed.

OPERATION
The vehicle speed signal is used by the EVO power steering system as follows:
^ The output current to the power steering control valve actuator is a function of vehicle speed and the steering wheel rotation rate.
^ When vehicle speed is less than approximately 16 km/h (10 mph), the output current is less than 100 mA and near full power steering assist is provided.
^ As vehicle speed increases, the current increases to approximately 600 mA. The current then remains constant at approximately 600 mA for vehicle speeds greater than approximately 112 km/h (70 mph). Conversely, as vehicle speeds decrease, the current decreases.
^ Vehicle speed is also used to determine the proper trim height of the vehicle.
^ At approximately 105 km/h (65 mph) the suspension system lowers the vehicle trim for a more stable high-speed profile.