Vehicle Speed Sensor (VSS)
WARNING: This page is about a different car, the 2003 Dodge Grand Caravan, 2003 Dodge Caravan, 2003 Chrysler Voyager, and 2003 Chrysler Town & Country. However, it is still accessible from the selected car via links, so may be relevant.
VSS delivers an input signal to Powertrain Control Module (PCM) to indicate transaxle output shaft speed. PCM uses input signal from VSS, along with TP sensor closed throttle input signal to determine if a closed throttle deceleration or normal idle condition exists. During deceleration, PCM controls Idle Air Control (IAC) motor to maintain a desired MAP value. During idle conditions, PCM controls IAC motor to maintain a desired idle speed.