Theory Of Operation
WARNING: This page is about a different car, the 2010 Dodge Avenger and 2010 Chrysler Sebring. However, it is still accessible from the selected car via links, so may be relevant.
The input and output speed sensors use a common ground circuit. The loss of this common ground results in the input signal being sensed for both. After a reset in neutral, and after observing a specific ratio, the Speed Check Fault Counter will increment. Because the speed sensors and the thermistor (temperature sensor) share the same ground circuit, this DTC may indicate a loss of the common speed sensor ground. In some cases this fault will cause a Gear Ratio Error DTC to be set.