Vehicle Speed Sensor: Description and Operation

LOCATION

Sensor mounted in transaxle extension housing.

PURPOSE

The Powertrain Control Module (PCM) uses sensor input, when it receives a "closed throttle" input from the Throttle Position Sensor (TPS), to determine whether vehicle is decelerating or stopped.

The PCM stores sensor input as distance traveled.

The PCM uses sensor input to control speedometer.

OPERATION

During idle, (no signals being received from sensor), the PCM actuates the Idle Air Control (IAC) motor to maintain desired engine idle speed.

During closed throttle deceleration, (slower signals received from sensor), the PCM actuates the IAC motor to maintain desired Manifold Absolute Pressure (MAP) sensor value.

Sensor generates 8 voltage pulses per axle shaft revolution.