Intermittent TC lockup when coming to a stop

[FamManTruck]

2002 4x2 Ford Excursion, 135k miles. I am struggling with figuring this one out and how to fix it without throwing parts at it....

The TC (I believe) is locking up as I come to a stop and causing the engine to stall. There are NO CODES stored in the DTC. The no code part is confusing to me. I have read on these threads that the TC Solenoid could be to blame, but I assume that would throw a code right? Another thread mentioned a cross leak of some sort...I don't understand that one.

Your help would be greatly appreciated.

[FamManTruck]

Ok, no replies yet...

It is still doing about once every three weeks.
Dealership test drive and scan showed no problems...you know the ol' "could not duplicate"...Never happens when a mechanic is driving it!

I blew out the cooler and did not see anything out of the ordinary. Air was moving thru the cooler.

I did find ATF in the connector at the rear of the tranny on top. Solenoid leak? Could that be the problem, with no codes?

[Turbostang500]

When it does it will it do it repeatably a few times?
Reason im asking, if it does or you know its coming, try putting it in neutral and see if it still dies.
If not then it could very well be the tc staying engaged.
from what i know of thar system, the pcm doesnt sense the active state of the tcc solenoid. Just applies 12v when it should engage. If this is the case, then the pcm wont know if it actually releases and wont throw a code.

I would just try the neutral thing if you can catch it. Also, if you do that and it doesnt stall that time, beware of putting back in gear!!! Might still be applied and could cause your truck to lunge forward.

[FamManTruck]

When it does it will it do it repeatably a few times?
Reason im asking, if it does or you know its coming, try putting it in neutral and see if it still dies. If not then it could very well be the tc staying engaged.

YES, even if the engine stalls, I start it up and it typically does it immediately again. It usually requires a shut down and wait prior to restart, before it goes away. The problem goes away when placed in N. Also does it in R, 2 and 1.


from what i know of thar system, the pcm doesnt sense the active state of the tcc solenoid. Just applies 12v when it should engage. If this is the case, then the pcm wont know if it actually releases and wont throw a code.

That makes sense. Do you think the wet connector I mentioned has anything to do with it?

I would just try the neutral thing if you can catch it. Also, if you do that and it doesnt stall that time, beware of putting back in gear!!! Might still be applied and could cause your truck to lunge forward.

I know. It has happened in traffic...BAD!

Thanks for the reply! I appreciate all the help/guidance I can get before I start throwing parts at it, or worse yet, a new tranny.

[Turbostang500]

I am gonna say it is the torque converter clutch solenoid.
It sounds like it is applying but not releasing. If you were experiencing
a problem of it not applying all the time i would say yeah the harness.

A 12v signal to the tcc solenoid applies it and allows trans fluid to go into the tc
and apply the clutch. When the signal is dropped it SHOULD cause the solenoid to open
and release the pressure. I think your solenoid is sticking closed and not allowing the pressure to be released which holds the tcc engaged.

It shouldnt be that expensive or that hard to change.

[FamManTruck]

Thanks for your help. I appreciate you taking the time to share your thoughts.
I will post here with updates as I make progress in order to help others that may have a similar problem.

[Turbostang500]

No problem chief.
Hope ya get it fixed!

[FamManTruck]

Here's an update...

I cleaned out the wet Solenoid connector and applied Dielectric Grease to the pins. So far, so good...No more stalls/unintended TC lockup while stopping. Hopefully a short?

I'll let you know if anything changes.

[Turbostang500]

Huh.....never would have guessed that!

Glad it is workin out for you!

[Brooksy]

So how about an update? My truck has been doing the exact same thing. Since it has started to warm up the truck is doing great, but it seems to happen after a longer drive. 30 to 45 minutes of travel. When driving around town i have not seen it happen. And yes the truck lunging forward before it dies in traffic really blows! Also what conector did you check, i have not got under the truck to look, just looking for a starting spot.