P0500 No Vehicle Speed Sensor Signal

NAME OF CODE
P0500 ($23) No Vehicle Speed Sensor Signal

WHEN MONITORED
With engine temperature greater than 104°F, MAP approximately 350 torr, (or MAP vacuum 15 to 16") and engine speed between 1400 and 3000 RPM.

SET CONDITION
No signal from the vehicle speed sensor for more than 15 seconds on two (2) consecutive trips.

THEORY OF OPERATION
The vehicle speed sensor is a hall-effect type sensor used to detect the vehicle speed. The PCM calculates the vehicle speed based on the VSS signal. The PCM supplies 5 volts to power up the sensor and also supplies the sensor ground. The PCM also supplies a 5-volt pull-up voltage to the sensor. The VSS signal is created when the sensor alternates the 5-volt pull-up from high to low.

POSSIBLE CAUSES
- Open or shorted signal circuit
- Speedometer pinion damaged
- Open 5-volt supply circuit
- Open sensor ground circuit
- Failed vehicle speed sensor
- Failed PCM