Converter lockup too soon?

[michael0584]

I was driving to my parents on Christmas going about 70mph when it felt like the trans was dropping in and out of 4th gear or slipping, I pulled over and checked the fluid and it was fine. I got back on the freeway and left it in drive to keep it out of 4th gear. It drove fine the rest of the way and when I got off the freeway I put it back in OD. It shifted fine and the converter locked up at 50mph. Now that I feel the converter locking up I'm sure it was locking and unlocking on the freeway. I really don't think it has been locking up at all, or at least not at 50mph. It really seems to lug the motor. It has been locking up fine now no unlocking on the freeway or anything. When it locks at 50 I can slow down to 45 and it will stay locked, If I try to accelerate slowly it will stay locked and the engine seems to be lugging, it feels jerky like maybe its missing. If I punch it the converter will unlock. I can step on the brake and the converter will unlock then Immediately lock back. How does the ecm determine when to lockup the converter? Is it a set speed? I don't think the engine is missing, its been about 10,000 miles since a full tuneup.

 

[michael0584]

By the way I have 3.42 gears and 31" tires and its a 700r4 trans, that is the upgraded version with the rainbow casting mark on the side. It has been rebuilt before just not sure how many miles are on it. 40-60k???

 

[michael0584]

I think its definitely locking and unlocking while on the freeway. It was doing it on my way to work this morning. I tried pushing the brake and it didn't drop out so I don't think it was locked up. I'm guessing the solenoid in the trans is going bad. How difficult is it to replace?

 

[michael0584]

I dropped it into 3rd and it seemed to do the same thing, I will drive it some more to verify that.

 

[gone huntin]

I just went through something similar. Read here. http://coloradok5.com/forums/showthread.php?t=263974

 

[michael0584]

mine is locking and unlocking in 3rd too. reading your thread your would hold fine in 3rd. I'm not sure what causes it to lockup in 3rd or if that solenoid locks it up for 3rd and 4th.

 

[gone huntin]

I was mistaken, it wasn't holding in third when I test drove it with the guy at the trans shop. It would hold lockup cold, but once the fluid got to temp it wouldn't hold anymore.

 

[michael0584]

That seems like mine, will lockup cold but once its warm it jumps in and out then is just out all the time.

 

[michael0584]

How can I keep it from locking up until I can tear into it on friday. I don't like it dropping in and out. I'm gonna drive in 3rd just want disable lockup a few days.