03 Duramax/Allison Shifting Problems

TurbDies2500 · 11-02-2009, 08:08 PM

Hey guys, I have a 2003 Duramax with about 130,000 miles on it in great shape. I have kept up with all the maintanence and have had not problems with it. I pull a trailer and plow with it so it gets its share of work. Recently when I am driving down the road at any speed between 20 and 60 and I go to step on it, it will lag and down and won't shift up to the next gear. It will just rev up to almost about 3 grand and then just stay there and bog down. I have to let of the gas and then feather it back on to get it to shift into the next gear. Typically happens between 3 and 4. It does not happen all the time either. The problem comes in and out. The tranny seems to be working great except for that. I am not sure if it is an electrical problem or what.

Anyone have any ideas?? I need some help figuring this out. I rather try and figure it out without paying someone for diagnostic time.

Thanks.

tate07lbz · 11-02-2009, 08:12 PM

have you serviced the tranny?

**slimwolf** · 11-02-2009, 08:13 PM

When was the last time changed your fuel filter? Sounds stupid, I know. But I'm serious

TurbDies2500 · 11-02-2009, 08:18 PM

Both the fuel filter and tranny service have been done. I did the fuel filter about 8-10K ago and the tranny fluid and diff fluid was replaced two weeks ago.