I did a search about 8 pages deep and could find a answer.
So I have a built 4l60e and a yank tt3000 that both are 4 weeks old. PCM is tuned for both. I was taking off under normal throttle with the tow haul on. At around 40mph it feels like the is being slowed down. As if I was lightly applying the brakes then letting of, back and forth ever second. Turned the tow haul off it shift in OD and it goes away. The next day I drove and it did do it for the first 15 min so I got on it. It ran normal. 10 min after that it did it again only in 3rd gear at around 40mph under normal throttle. It did so it once in 2nd going up a hill under normal throttle. So it seem to only do it when the tranny temp are over 150. It has never been over 190. The RPM dos not change when it is doing it. And the tranny fluid dose smell a little weird. But not really brunt. I scanned for codes and have none.
At first I though it was the lockup solenoid but then with the fluid not smelling right I don't know. Maybe have 8 miles on it after it first did it.
Any ideals.
Thanks

 

Who did your tune? I've heard some weird stories with the tow and haul button feature. Anywhere from no od, no lockup, no downshifts. I think ther might be some really funky tables for the computer with this option. I am no tuner but two of the guy's had the wait for me tune. It would be best to get with your tuner.

 

Nelson. Vince the same PCM has been it for four weeks.Untouched since install. Do you think that it still might be the tune. Can it just change all of a sudden?

I took it to the tranny shop today. Went with a test drive with the owner. Piece of **** wouldn't do it after 5 min of driving. Then on the way back to his shop it started doing it really bad. In second gear @1500 rpm with out the tow haul on. He told me to lightly push on the brake while it was doing it. Said that will force the covert to un lock. It still did it the whole time. Then we brake stalled it at 1500rpms, it didn't do it. Still have no codes. So he is hooking it up to a tranny scan software to take some logs.

 

No I don't think the tune will change on it's own. Lets see what the tranny scan say's.

 

Hey Vince have you ever heard of this happing?They are using Tran X 2000. When logging with it my truck shifts in to 1 & 2 fine then in to 3rd it goes in to fail safe mode, but only when they are logging. If they use Tran x to force the shifts it works. If tran x is not hooked up you can take the truck out and drive it 1st through OD it doesn't go in to fail safe. It still dose what I post in the first post. The only other thing they found is the pump going to 100% when it not supposed to.
They have check the wire hook up for Tran x. Even hooked it up to a different truck and it works fine.
Any clue
Thanks