'96 Jimmy Auto Tranny Issue

[tvpierce]

My brother in-law is in a tight spot with his ’96 GMC Jimmy (S-15) 4WD/4.3 liter. It’s a daily driver, and his wife just got laid off, so they don’t have much (read: none) money to spend on it. My experience with GM products is pretty limited, so I was hoping someone here could offer some expertise.

 

The tranny is a 4-speed auto, and it’s acting up… here’s the problem: The tranny shifts fine into gear with no delay, and shifts fine into second gear while driving. But when it goes to shift into 3rd gear, he says it's as if it’s “popping/slipping out of gear”. He can drive the truck fine if he puts the gear selector into 2nd gear (thus keeping the tranny from shifting past 2nd). Obviously, driving with only 2 gears is not a long term solution, but at least he can limp around town.

 

Any thoughts on this? Is this a common failure with these transmissions? Is it something that a simple drain/flush will correct, or are we looking at a rebuild/replace?

 

If it requires a rebuild/replace, would the 4-speed auto box from a '91 Chevy Astro (2WD) be a direct swap? (I have access to one that's headed to the salvage yard.)

 

Thanks in advance for your help on this.

 

Jeff

[GM-Tech]

Not a common failure that I'm aware of, and certainly nothing that a simple drain and refill is going to correct. Sounds like it needs to come apart.

 

The '91 trans won't work. His '96 is electronically controlled, the '91 is not.

[tvpierce]

Not a common failure that I'm aware of, and certainly nothing that a simple drain and refill is going to correct.  Sounds like it needs to come apart.

 

The '91 trans won't work.  His '96 is electronically controlled, the '91 is not.

 

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Wow... thanks for the quick and informative response.

 

(BTW, I really like your signature -- got a good chuckle out of it.)

 

Jeff