Not my truck, This is for father inlaw

Here is the problem,
Transmission failure approx 240000 miles, bring it in, get rebuilt tranny, local shop.
lasts about 5000 miles(3yr warranty)
Transmission has to go to local GMC dealer for next tranny.
Get about another 5000 miles, fails again.

3 more transmissions under warranty, averaging 55 miles each.
every time the same thing, 1st 2nd fine, then rev like neutral, forward clutch pack roasted.(thats 5 now)

The last time(last week) they hit him up for tps(270$) same thing, 60 ish mile roasted again.

Gm told him last time no more warranty.
Truck is driven lightely and pulls a load rarely and nothing excessive.

Any ideas? wiring? computer? and how to test?



any suggestions would be appreciated,(email if preferred, corkumbrian@hotmail.com)
Brian

 

Has cooler n lines been flushed?

 

Dealership claims lines and cooler flushed every time...on the same turn, they also claimed no DTC's found i believe every time as well , but when i hooked up a scanner myself, first thing that popped up was low tps voltage, was .23volts instead of .50 volts, so i corrected the position just before we brought it in for the last transmission.(62 miles outta that one)
The voltage sweep was smooth with no drops, but did come a hair short of 4.5 volts(4.27 ish) per scanner readout.
They did change the tps the last time for what reason i have no idea.

 

I've heard that a bad ECM can cause transmissions to burn up on some models. I'm not really sure if this applies to the 93 I know that it does to 97s when mine went out still under warranty it was one of the possibilities I checked into turned out the shop I had do my rebuild (I was out of state so I couldn't go to a trusted shop) just didn't know what they were doing and the new one Is running strong with 3k miles on it but it may be worth checking into just a thought

 

What trans are they installing?
4L80E or 700R4?

 

possible lip seal for apply piston being rolled during install?

 

Any lift in the burban? Big tires? Re-geared?
Any adders to the engine? Boost or turbo, propane?
Any noise from transfercase (if its 4x4)
Pools of anything before failure?
New burning smells?
They replacing the torque converter each time?
Any tranny fluid showing up in your anti-freeze?
They test your flywheel for true and straight balance?
Where is your exhaust plumbed? anywhere near tranny coolant lines or near housing not heat shielded?

 

I have a 93 6.2 that went through several Transmissions as well.I finally parked it and purchased a Duramax.
It kept bugging me why know one could figure out the issue.The transmission intermittently acted really random with hard shifting and locking /unlocking the torque converter at wrong times .I was finally told to try freeing up the fuel pump advance piston as they often lose the full range of motion or sieze up . I used a long flat screwdriver to reach it ,a flash light and some silicone spray to lube it and amazingly once I freed it up,as it was somewhat stuck, the truck shifted like new and allowed us to begin to use it again.I couldn't believe it took so long to figure that out.