Thread: Vehicle Speed Sensor????

Hopefully Trannymany will step in here and offer his insight. The erratic speedometer would make me think of the VSS as well. But the tranny chugging or not shifting would make me look at the Throttle Position Sensor. I guess it could be a wiring issue with the VSS as well, but again, I'll stop speculating and let Trannyman offer a much more knowledgeable and expertise based insight.

With no or an erratic VSS signal the trans function is directly related. When the pcm doesnt know how fast you are driving then it has no idea when to make the shifts or command lockup. A scan tool is the only way you are going to know what the signal is doing going to the pcm and that it is reading correct speed or not. If the differential is failing then a lot of metal can accumulate on the sensor and cause erratic readings. Also in a few rare cases it has been noted that the reluctor ring on the diff can be loose and cause this but I havent personally ran into this. Get ahold of a scan tool if you dont have one and watch the VSS to make sure you are getting input.

Anyone have any idea how to change the Input Speed Sensor(02 3.1L)? I keep getting P0716. When the service engine light comes on I reseat the ISS plug and the light goes back off...after a short drive. Does this require trans removal? I'm not sure if its the sensor or the plug. If its a simple process I might as well change the sensor. Ideas?

Generally the input speed sensor is not at fault when that code sets. The reluctor wheel inside the transmission has three pins pressed into it and over time the can hammer loose and eventually get hammered out of the wheel completely and when this happens the pcm has no input speed signal. The sensor will ohm test just fine but cant read anything because the reluctor wheel is no longer spinning as it should though it will float against the drive sprocket and move a little but nowhere near what it should. It is quite a big job to dig into as it requires lowering down the drivers side front support cradle and lowering the trans at which point you can remove the side cover of the transmission. Once you are this far into it you can unplug and remove the input speed sensor and take a finger and reach into where the sensor goes and see if you can move the reluctor wheel freely with a finger, if you can it means you have to remove the pump, valve body, and channel plate to have access to replace the iss reluctor wheel.