I have a 700r4, and when going into work in the morning the TCC unlocks after awhile. What I do is warm up my car, and start heading for work. It'll go through all 4 gears and stay in 4th until I reach about 135F. Once I reach 135F, the TCC will lockup. I'm assuming there is some type of sensor that tells the computer its okay now to lock. But now, after say about 20 miles it will unlock. The highway I drive on has no hills big enough to put any kind of load on the driveline or engine. So I thinking that maybe I'm over cooling my tranny and its telling some sensor that it needs to warm back up by unlocking the TCC. Does this sound reasonable? If so, what sensor? CTS? Is there some sensor in the tranny that does this?

I have a big external cooler installed and I'm by-passing the stock radiator cooler. My TQ is an ACT 9.5" 2400 stall.

Any and all comments are welcomed, thank you.

 

There's no trans temp sensor...

AFAIK the only important things are coolant temp and vehicle speed and engine vacuum. If you're coolant temp is too low the ECM won't lock it up. Or if the vehicle speed is low, or if the vacuum is low (low vacuum = high load = foot on the floor).

Some kind of a scan tool would be very helpful, to find out what the ECM thinks of the world it's living in.

 

Thats the weird thing about this.. my tranny is from Pro-built and if I recall he puts in a temp sensor in the pan.

My tranny temp gauge reads about 135F and starts to drop as I get closer to work by a few degrees. I assuming since its cooling off. My engine temp gauge reads about 135F by the time get there, so its steadily climbing. Is this too cold? Maybe my CTS is telling the ECM to drop the tranny out of lockup?

I have a scan tool, but my SES light hasnt come on so I dont know if that will help. Thanks for any replies.

 

If he did, it goes to a gauge. The ECM knows nothing about any of this.

 

Hrmm not sure. Dana from Pro-built mentioned that the temp sensor sits in the oil and is bolted on to the valve body. He said that I could drop the pan and remove the sensor, and just splice the two wires together. The sensors job is to make sure the oil temp is warm enough to allow lockup I believe. If I splice it, then it'll lockup no matter what the temp is.

I'm curious to know if others have to wait until a certain temp before their tranny will lockup?

Thanks again.