Without Antilock Brakes

Diagnostic Chart:

Schematic:

On vehicles equipped with manual transmissions and without antilock brakes, the PCM receives vehicle speed signal from the vehicle speed signal conditioner module. The signal is a square wave based on the AC signal generated by the right front wheel speed sensor. The PCM provides a 5 volt pull-up and the vehicle speed signal conditioner module pulls circuit 1909 to ground to generate the signal.

DTC PARAMETERS
DTC P0502 will set if vehicle speed signal is less than 3 km/h (2 mph) for 5 seconds when the following conditions have been met:
^ Engine speed is between 1700 and 3600 rpm.
^ Throttle position is less than 1%.
^ Engine vacuum is between 70-80 kPa.

DIAGNOSTIC AIDS
The vehicle speed signal is checked continuously. If vehicle speed signal is missing the speedometer will be inoperative.