Vehicle Speed Sensor (VSS)
VSS is located on transaxle. See Fig 1 . VSS generates 4 pulse signals for each rotation of speedometer driven gear. PCM will interpret VSS input along with TP sensor closed throttle input.
These inputs allow PCM to differentiate between closed throttle deceleration and closed throttle idle (vehicle stopped) conditions. During deceleration, PCM controls Idle Speed Control (ISC) servo to maintain desired manifold pressure value. During idle (vehicle stopped), PCM controls ISC servo to maintain desired idle speed.