Vehicle Speed Sensor: Description and Operation

COMPONENT
Vehicle Speed Sensor (VSS)

FUNCTION
Detects speed going out. Outputs frequency signal to PCM. PCM controls operation as follows:
1. Fuel injection
2. Ignition timing
3. Shift/torque converter clutch scheduling
4. EPC

REMARKS
Uses a variable reluctance sensor. Sensor generates a sine wave type waveform with a frequency.
^ High frequency as vehicle velocity increases.
^ Low frequency as vehicle velocity decreases.

Installed in transmission (4x2) or transfer case (4x4).
If EPC solenoid is shorted to ground, PCM outputs DTC for VSS. Diagnose EPC solenoid first, then checks VSS.