4L80E lockup clutch modifications

[Kick3500]

alright, got a K3500 with an intermittent lock up clutch problem

what fixes are available for something like this

I'm looking at minimum replacing the PWM solenoid and maybe doing something to the valve body.

any input would be appreciated.

[JadXtreme]

I'm having the exact same problem with mine. Only mine has just 90K miles on it. Had it diagnosed and was recommended to change TCC PWM soleniod first and it might fix it; that didn't fix it. Next, suggested that it is the torque convertor. Said that the torque convertor had a high slippage when he had his scan tool hocked to it monitoring it. Mine was reading 350-375 rpm slippage when 110 or so is max. I replaced the TC and rebuilt the pump booster; still not locking up TC like it should. Only other thing it can be is the valve body. Right now I'm in the process of getting ready to replace the valve body with a remanufactured one. Hoping that will fix it. I probably won't get to try that till next weekend maybe.

How many miles are on your tranny? I've done the replacing parts stuff myself and had it diagnosed at other places. Right now, with the diagnosis + TCC PWM soleniod + 6 qts Valvoline HM ATF + filter + TC + having pump booster rebuilt + 14 qts Mobil 1 full synthetic ATF + exhaust flange gasket (dropped exhaust and damaged existing gasket) = about $675 and it still ain't fixed.

I suggest to take it to a good local transmission guy and tell him all that it is doing. Right now, all I got left to replace or fix is the valve body. Maybe it is just your valve body. Have him look at that. When I took my tranny in to have the pump booster rebuilt, he was supposed to look over everything really well to make sure that the clutches/rings looked good and that the valve body was all good. None of the bores were checked though and maybe that's what mine needs.

Hopefully, you'll have better luck diagnosing it than I've had.

[Kick3500]

truck has 97k miles.

its not a big problem, its not like it doesn't work. its just doesn't work some of the time.

[JadXtreme]

Yeah. It caught me off guard because my truck has so few miles on it and I thought that something was majorily fixing to break even worse. It kills my gas mileage though the way that mine is right now. Since I've done spent all this time trying to fix it, I'm gonna go ahead and try to fix it. Like I said, TCC PWM soleniod, new torque convertor, and a different PCM hasn't fixed it so it must be in the valve body. I'd look there first.

[dave89iroc]

I replaced the PWM solenoid and TC on mine, that fixed it

[2COR517]

You might try a Superior shift improver. Ordering one for my 4L60 this week.