Circuit Description

Vehicle Speed Sensor (VSS) is located behind instrument cluster. PCM supplies a 5-volt signal to VSS. While vehicle is moving, a reed switch inside VSS will open and close, 4 times per revolution, toggling 5-volt signal high and low. PCM converts this toggled high/low voltage into a vehicle speed that is displayed as MPH (KM/H). DTC will set when vehicle speed sensor signal in not present during fuel cut-off mode for greater than 4 seconds.

When DTC sets, MIL will illuminate after 2 consecutive ignition cycles in which diagnostic runs with active fault. PCM will record operating conditions at time of failure and store information in freeze frame buffer. PCM will enter Fail-Safe Function and stop Idle Speed Control (ISC) operation.