Code 639...Transmission Speed Sensor.

[pacodiablo]

My OD off light began flashing today in my 95 Explorer. The only code it spat out was 639, which is a fault in the transmission speed sensor circuit. I did drive the truck on a muddy wet trail earlier...is it possible that messed up the sensor? Is it okay to drive the truck? What/where is this sensor and what kind of money damage am I looking at? The truck shifts fine and the fluid is good.

 

[pacodiablo]

Is the TSS the same as the VSS? Speedometer works fine, but I haven't been able to find any mention of a TSS online or in Haynes.

 

[pacodiablo]

Apparently some moisture got in the connection. It dried out overnight and everything is fine now. I will clean/put dielectric on all of the connectors under the truck soon though.