Without EATX (Electronic Automatic Transmission Controller)

NAME OF CODE
No Vehicle Speed Sensor Signal

WHEN MONITORED
With engine running more than 31 seconds, engine temperature greater than 180° F, transmission not in park or neutral, brakes not applied, engine rpm greater than 1800, and MAP vacuum less than 11".

SET CONDITION
No signal from the vehicle speed sensor for more than 11 seconds.

THEORY OF OPERATION
The vehicle speed sensor is a hall-effect type sensor used to detect the transmission output shaft speed. The PCM calculates the vehicle speed based on the VSS signal. The PCM supplies 8 volts to power up the sensor. Sensor ground is supplied by the PCM. The PCM also supplies a 5.0 volt pull up voltage to the sensor. The VSS signal is created when the sensor alternates the 5.0 volt pull up from high to low.

POSSIBLE CAUSES
- Open or shorted signal circuit
- Speedometer pinion damaged
- Open 8-volt supply circuit
- Open sensor ground circuit
- Failed vehicle speed sensor
- PCM failure
- Connector terminals
- Connector wires