1994 K3500 4L80-E Transmission problem

[APDLawDog]

I have a 1994 K3500 Crew Cab Dually 4x4 with the 7.4L (454) and the 4L80-E transmission with 44,000 original miles. It starts out shifting fine until I hit 45mph then the transmission acts like it is in neutral. I can rev the gas (tach goes up) but the truck doesn't go any faster. It will continue to slip until I stop, turn off the truck, and restart it. It will then shift OK until 45mph. I took it to the transmission shop and they replaced both shift soleniods and then determined it was the DRAC/VSSB by checking the output of that unit with a computer. I got another DRAC/VSSB and nothing changed. So, either the second DRAC/VSSB unit I purchased has the exact same problem as the original, or there is something else wrong. HELP! Anyone have any suggestions?

[txab]

No need for multiple posts on the same subject.

 

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