Shifting issue

JPEELER49

MEMBER
2004 GMC YUKON
5.3L
V8
2WD
AUTOMATIC
214,000 MILES

I have the vehicle listed above that stopped shifting past second gear. I’m thinking it’s something electrical because I don’t have any hard shifts or anything that would make it seem like something mechanical. I was driving it fine to work with no issue until I went to leave and that’s when it stopped shifting properly It shifts fine into reverse, first and second, but once it’s supposed to hit third the rpm just increases and I can only go about 40 mph before it starts shaking. I replaced the speed sensor hoping that was the issue, but no luck.

Monday, October 28th, 2019 AT 6:09 PM

1 Reply

STEVE W.

MECHANIC
15,451 POSTS

Welcome to 2CarPros. Your description sounds like a very common issue in that transmission, burnt 3-4 clutch discs that are causing the transmission to slip when it tries to engage 3rd gear. That would cause the slipping and shudder you have. There are a few common causes for it but the more common ones are related to worn seals and defective parts, namely the 3-4 backing plate that flexes and lets the clutch pack slip.
First thing I would check would be the fluid. You want to see nice clean red fluid that is maybe just a bit brown. If it is dark color or has grit in it then that is more evidence of the damage. Electrical wise there are only 2 solenoids in this transmission. Both are used for the 1-2 shift and reverse. For 3 and 4 the clutch pack is the only part that is used for those gears that are not used in other gears. As such you are more likely looking at a rebuild or replacement, not an electrical issue.

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Monday, October 28th, 2019 AT 6:41 PM