tc lockup

[Jeff Waller]

I a 2002 f350 superduty 7.3 automatic.When getting on the highway the tc will lock and unlock 4 or 5 times till up to speed.Had a tranny shop drive it with there scanner and everything was working has it should.they said it was a issue with something telling it to do it. but would just be guess at what to replace.had it scanned at a ford dealership and no codes there also.

[Hank]

My suggestion is to take it to a shop known for building transmissions for the sled pullers and drag racers. They are usually the guys that can help the most. I have an AutoEnginuity scanner that I can hook up and drive and see when the TC locks up. Find someone with one and make sure that it really is doing what you say. There should be codes left behind if so?

[ipz2222]

If the compter is telling it to lock and unlock, lock and unlock, the it won't set a code.
Get a scanner that can read data and watch the boo pid.. brake on off.

[Ryan Rønning]

A quick check would be to see if the wire that sends the grounding signal to the TC is shorting against something metal.

[ipz2222]

Good call, ryan.

[Jeff Waller]

Would that be the purple wire with yellow strip. I beleave thats the wire you use when you install a lockup switch.