For about the last week or so, I can be just cruising along around 55 to 65 and the torque converter will just unlock and lock right back up. Only at steady throttle. It doesn't do it under a load. I pulled around 12000 to 13000 lbs yesterday with no trans slippage. It unlocked in a steady straight stretch but locked right up. Pulled up probaly a 25% grade even.

Does this sound electronic? Where should I start?
Thanks

 

thats more than likely another tach sensor http://www.forddirectonline.com/ you can get them for $62 to the door.they are a pain to find on the website though i literally was trying to hunt the link down 5 minutes ago for another thread

 

Ok I'll try that.
Been so busy lately i havent been able to get on.
Thanks Rupe

 

has your tach been goin goofy or anything?usually thats the main thing that gets an e4od to act up

 

Could be a tach sensor, Speed sensor, or throttle sensor.

What I would do is first try to narrow down where the problem really is before replacing anything. Sometimes it works, sometimes it doesn't and you have to swap parts out anyway until the solution is found.

Since the symptoms seem to be linked to engine load, I am more inclined to think the throttle position sensor* is either bad, or not adjusted properly.

Normally, the truck is supposed to unlock the TC when ever you let off the pedal completely. If its not adjusted properly, the computer might be mistaking light load cruise conditions for idle throttle position.

The sensor is easy to test since is basically just a potentiometer. Idle should be 0.8-1.2V and full power should be 4.0-4.5V. The transition from idle to full power position should be smooth and clear without any dead spots or spikes on your volt meter.

Faulty brake light wiring could also be to blame, since the computer will also unlock the TC as soon as the brake lights come on.

Tachometer and speedometer need to read perfect for the transmission to function properly. Any fluctuation in the tach or speedo readings indicate a problem there (usually the related sensors, VSS and tach sensor).

 

i have a feeling that it is your speed sensor,reason is because i had the same problem while i was going down the road...the converter would unlock then lock bace up.....but also at the same time i noticed that the speedo would go crazy and i would somehow end up 5-10 miles backward on my odometer, so i went down to the trans shop thinkin they did something wrong (it had just gotten a new tranny) then after lookin up the tc's and lookin at other things they decided to look at the speed sensor, sure enough it was covered with metal shavings,my rear end fulid was shot when i changed it, it looked like sludge(shows the ppl i bought it from didnt take care of it). but i do agree that it could be your tach sensor as well....but i experianced the problem with the VSS its not that hard to take out...right on top of the rear end one bolt holds it in
-94 f-240 7.3 idit

 

Trailer wiring and the brake light circuit may be where your problem is.

I have seen some strange trailer wiring cause rather strange problems before.