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 18O°F, transmission not in park or neutral, brakes not applied, engine rpm greater than 1,800, and MAP vacuum less than 10 in.

Set Condition:
No signal from the vehicle speed sensor for more than 6 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 from cavity 44 to power up the sensor. Sensor ground is supplied by PCM cavity 43. The PCM also supplies a 5.0 volt pull up voltage to the sensor from cavity 66. 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