Guys, have a buddy that is having this problem, happens when he is going down the highway maintaining speed (like a cruise control situation). Locks/unlocks/lock/unlocks all within 2 seconds, then works fine for a couple miles and then happens. On his drive to work(15 miles) maybe happens 4-5 times . Doesn't do it in third gear and it didnn't do it while actually having cruise control on in OD?

TPS shouldn't be causing it as he replaced it, what about TCC. I know when I step on my brakes going down the highway my converter unlocks when I tap the brakes. Could that be bad? Let me know what you guys think.

here's what he said
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It's always something I swear to God....

My most recent problem is cruising down the highway at steady speed with my foot just BARELY on the gas the torque conveter starts locking / unlocking like crazy. really quite annoying, not to mention hard on everything and bad for mileage (like i get that anyhow). Ground is level. Truck is in OverDrive.

I've got no warning lights. Replaced the Throttle Position Sensor last night and it didn't fix anything (sensor was bad, return spring had failed on it).

So besides a bad torque converter clutch soleniod what could it be? I can not afford the time to drop it and looksee inside for issues. Gotta keep it running.

Does the 4L60e use a brake switch to lock / unlock the converter as well? Could this be bad?

Problem does not exist in 3rd gear that i've been able to replicate at all. Thanks for the input!
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TCC lock up soleniod.......I've replaced these some several times!

 

I guess it didn't do it while in cruise control. there is a brake and cruise switch taht causes the TC to unlock, right?

 

what do you feel when it unlocks? after you hit the brakes and it unlocks, what happens. i dont think ive ever felt it.

 

I have been having something very similar to this occuring for the last two years. The tc acts the same as mentioned above. With this addition, my truck, will while crusing on flat highway maintaing constant speed, tc is unlocked until increased load is realized. For instance the grade increases the tc locks, once the grade or the load decreases the tc unlocks. The tc does not seem to do this until temps are warm. This could be 80 miles from home on highway only road trip or 10 miles across town during traffic.

* Just installed a aeroforce scan guage, going to monitor what the engine / tranny temps are when this starts to occure.

This has become much more noticable since the Trail Blazer TC install. Only because the RPM's increase that much more while slipping.

I have mentioned this on this board before as well as to Westers my tuner. At that point the question was are misfires causing the tc to unlock. The aeroforce hasn't shown any misfires to date.

Wondering if guys tc locks back up when load increases?

How difficult is the tc solenoid ot replace? Tranny in or out?

 

mine did this everytime my pos local built tranny was about to blow, everytime bing the pump... could be different tho

 

check the fluid level!!! mine was doing the EXACT same thing, turns out i was low. topped off and it stopped.

 

could be the lockup clutch going out

 

ok, looks like having the cruise control didn't really affect it as it did it this morning. Looking at the TCC and brake switch now (anyone know where the latter is?)

 

Has anyone messed with your TCC lock-up tables? If you have the TCC lock at a certain point and unlock a tic under that,...you may be floating in that area where lock and unlock happen when driving at that TPS and speed.