Is your car a plain 300, with a 2.7 litre? Here is a test for front sensor'

1. Check for battery voltage to the wheel speed sensor on the Dark Green/Light Green wire.

2. Check the output of the sensor while backprobing this same 12 volt circuit. The voltage will only change 0.2 of a volt, while slowly turning the wheel.

3. A magnet can be used on the end of the speed sensor to pass it back and forth to see if the speed sensor picks up the signal.