Vehicle Speed Sensor (VSS)

VSS generates 8 pulses per sensor revolution. VSS input is used by PCM to determine vehicle speed and distance traveled. PCM interprets speed sensor input along with TPS closed throttle input. This enables PCM to determine if a closed throttle deceleration or normal throttle idle (vehicle stopped) condition exists. During deceleration, PCM controls Idle Air Control (IAC) motor to maintain a desired MAP value. During idle (vehicle stopped), PCM controls IAC motor to maintain a desired idle speed. PCM also uses VSS signal to maintain set speed during cruise control operation.