[GoGetter]

Bought 2002 HD truck 3 weeks ago, had it checked out at dealership before I bought it. The problem is when it shifts to 2nd or 3rd or 4th range when driving it normal, occasionally the engine does a brief rev-up during the shift. The shift is not sluggish. I believe it is mainly 3rd gear it does it in and only once in awhile. You can be driving around town and everything is shifting great and all of a sudden it throws this strange shift in. Anyone have any ideas? Do I need to get trans rescanned? I understand the 3rd clutches can have issues in this Allison but I can detect no slippage whatsoever. When you run it hard everthing shifts smooth and snug, its when the truck is run normal is how I drive this problem pops up. 109,000 mi, vin# 1GCHK23182F147678 This truck was driven to and from work, it has never pulled, next to perfect. Any Ideas?

 

[GoGetter]

Better Description

Its GoGetter again. Really need you guys help. I'll will try to describe it clearer.
When trans is finalizing the shift the engine does a very brief rev -up, its like you could blip the throttle between the shift points and on the other hand it appears like the TCM is calling for a brief rpm increase. It is definitely annoying and the thing I can't figure out it only does it once in a while. located in Missouri, between 20 and 35 degrees most of the time. Counting on you guys for your imput. See anything like it?

 

[HDBrad]

That was happening to mine. This is how it will play out.
1. Happens every once in awhile.
2. Then more frequently.
3. Next it will throw a code. Probably will have something to do with incorrect gear ratio.
4. Then you're getting a new/rebuilt transmission because one of the clutch packs has failed.

I'd take it back to the dealer and beat them up about it until they fix it. They said they checked it out, but only the dealer really knows the truth. Besides, unless the TCM is generating a code, the only way to really check the transmission is to take it apart. I had recently had a trans service done on mine, (NOT a mechanical flush) and it started failing a couple weeks later. This is somewhat common. New fluid cleans out the old deposits and things start to fail if the transmission has not been cared for properly.

Sorry for the bad news.

 

[GoGetter]

Thanks Brad

I'm going to keep my fingers crossed on this ally, bought truck from individual and had dealership check it out just to get a second opinion. Thanks Dewey