QuestionI have a 1997 Z-71 GMC 1/2 ton pickup 4x4,with 90,000 miles on it. The transmission works fine on short runs or up to 25 miles. It shifts hard after 50 miles of steady running and I stop, and go to take off with a clunking noise in the rear end. Whats confusing is if I stop and shut off the engine for a few minutes,it will then run fine until it gets hot again. I have a code reader and it says transmission module is unstable. I would appreciate any assistance you can give me.
AnswerHi Dave,
That's out of my expertise, but you might want to check with a dealer to see if your truck is covered under a recall, or Campaign. I have heard of some of those transmissions being covered long after they should have gone off warranty. Lifetime even comes to mind.
Have you used any additives, or changed the fluid?
The clunking noise is probably the slip yoke splines.
Go to the following site, sign in,(FREE), and search for some key words...slip yoke, transmission, clunk, etc. Be in the correct vehicle area, cause you won't care about a clunk in a 1938 truck.
You will like the forum.
www.chevytalk.org
Van
