Town Car V8-281 4.6L SOHC (1991)
Vehicle Speed Sensor: Description and Operation
Vehicle Speed Sensor
The Vehicle Speed Sensor (VSS) is a magnetic pulse generator driven by the transmission speedometer gear.
The VSS produces 16 AC signals per revolution and sends this signal to the Electronic Control Assembly (ECA). The ECA converts this signal to a
vehicle speed value and stores that value in RAM memory.
The ECA uses this value to aid in controlling torque converter lock-up, coolant fan control, vehicle speed control, air/fuel ratio and ignition timing.
