Having an issue with trans . Tow haul quit in top 3 gears . Worked when new! Took it to dealer they said needs new shift lever. Changed out and it fixed manual shift but not tow haul. Now it has developed a bump. When you come to a complete stop it feels like someone bumped into the back. It happens about a second after I stop. But not every time.
My dad has an 01 GMC. Tow haul would go in & out by itself. He looked up under the steering wheel & saw some wires hanging down. Pushed them back in place, cabled them up & problem solved. Sometimes it's simple, sometimes not. Good luck.
List year & mileage of your truck. Check splines on slip yoke, could be worn. Also been reports of trucks not down shifting into first until after it has come to a stop, causing the "bump" issue. If you have a Tech2 or Edge CTS you can monitor trans shifting.
[QUOTE=gmcmax05;3784533]List year & mileage of your truck. Check splines on slip yoke, could be worn. Also been reports of trucks not down shifting into first until after it has come to a stop, causing the "bump" issue. If you have a Tech2 or Edge CTS you can monitor trans shifting.[/QUOT
is it possible you shorted out your battery boosting or shorted wiring. this happened to me and shifting system quit working properly. I bought a new computer on line and installed myself then took truck to GM and had it programed for $50.00.
The computer is simple to change and its mounted next your steering column It is called the TCM and you can get them online much cheaper than from the dealer. Takes minutes to replace. Transmission Control Module controls all your shifting from gear to gear and needs to be programed to your truck once you install it.
Live n learn ! Allison has two filters an internal and external . I did not know about the internal when I changed trans fluid and external filter . Just changed internal drives like new!
Allison trans
Linear Mode
