Thanks to you guys, I've suddenly become the 4T60E and 4T65E expert. (I really know very little but you all do and that makes me look good). Anyway, I have a problem with a 1999 Buick Regal, 3.8L, 4T65E. The speedometer goes bursurk and then the speedometer dies and then the transmission starts chugging and won't shift. At least that's the way it's been described to me. I first told him to install a new VSS and he did and it solved the problem. Then a week later it's doing the same thing again so he changed it again but this time it didn't fix the problem.

This seems like a VSS to me, but ??????? Any help is appreciated.

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.

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Scotty Hall
Bartlesville, OK
2001 Pontiac Grand Prix GTP
It whines a lot, but I like it.

The only limitation you will ever face in life is yourself!

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.

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4T65E Transmission Info
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