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TC unlocking then locking repeatedly

4K views 47 replies 9 participants last post by  layson 
#1 ·
when im cruising on the freeway with CC on after a while it will kick off then as i keep driving at the same speed the TC will unlock. get back into the throttle and it locks back up. When the Throttle is held constant or the speed is constant is when it unlocks. but any change in throttle or speed and it locks back up,

what could cause this? TPS? speed sensor? ive checked codes and didnt get anything.:dunno:

i need this issue resolved within the next 2 weeks because i need to make a trip with the truck.
 
#2 ·
want an easy fix? wire up a t/c lock up switch.. ha i got one it works nice for sure.
 
#6 ·
yea i called him last time this was happening and i thought i had it resolved, it was only doing it with the chip on now it does it all the time.

i will give him a call again tomorow. last time he said it didnt sound like its the TC itself but either a tuning issue or another issue with the truck.
 
#13 ·
Pull the chip and see what happens, if still bad get a scanner and check while driving and check for codes..leave chip out! Auto parts stores have scaners to loan or find a used Snapon MT2500 ..about $200-300. Worst case take it to ford have them check it..

Check ALL trans elect connections, Fluid levels, cooler hoses general double check.

Cary
 
#14 ·
Did that. It still does it without the chip. Fluid level is good and I used an AE to scan it and the only code I got was a P1280 so I replaced the icp still have the code. The PCM is commanding the TC to unlock. And I don't know why. It should be locked in 3rd and OD
 
#15 ·
Brake pedal sensor maybe? I know if the brake pedal is hit (whenever the brake lights come on) then it'll unlock the TC. Mine always stays locked, on the gas or not, until 35 or brake is touched.
 
#18 ·
Yea Brian the trans builder has been great but being thousands of mi away it's difficult to get some real help just what he says over the phone. I might try replacing the rear wheel speed sensor because it seems to be leaking around it.

For right now I wired up a manual lockup switch that bypasses the PCM so whatever is telling the PCM to unlock the TC is the issue I just can't seem to find it.
 
#20 ·
doubt that will fix it... i had that done for my TW chip and still does it, no matter how the chip is programmed its going to do it because there is something telling the PCM it needs to unlock the TC, Brian @ BTS said it could be anything electrical on the truck even a tailight :dunno: about that but according to the AE im using there are 484 sensors on the truck and any one of them could be the issue.
 
#21 ·
I am going to put it on the dyno with the computers hooked up to find out what is triggering it.

Mine is only in 3rd gear, and only if the rpm is 2500-2700, and only if the speed on the speedometer is below 60 mph. Over 60 mph at the same rpm it is fine. Thats why i replaced the speed sensor.
 
#22 ·
yea mine is in 3rd or OD, it just unlocks while im cruising at 17-1900rpms at 65-75mph and then runs up to like 25oorpms to keep the speed up because its slipping so bad the manual lockup switch is good for now but i need to figure out the real cause of this problem
 
#26 ·
No mine was fine for 2-3000 miles on the BTS trans and the stock trans never did it. It just started happening the past 500 miles or so. I will try a set of stickers but I don't think that's the issue. Because it's not hunting it just unlocks the torque conver and won't lock back up till it's cooled down. I'm hoping it's not a trans pump issue
 
#27 ·
Cooled down? Mine is not getting hot at all.

I tried the stockers just as a test two weeks ago, and the hill to my house where it always happens, it did the same thing.

It could be a trans issue or electronic issue. My trans builder has been a stand up guy with his warranty, so I know it will get fixed next week. He even met me 250 miles away to run the truck on the computers to see what the heck is happening, but the truck would not slip that day. Stand up guy.

Mine is still running good for now, just make sure it's over 60MPH in 3rd before flooring it. I will live until next week.

I am glad now who I picked to build the trans, because now with issues they are being taking care of. I could be SOL at this point.
 
#28 ·
i should have said gotten cold haha, it doesnt barely get above 140 but after it gets up to 140 or so it unlocks then heats up quick because its always slipping it will get up to 180 within 10miles

yours doesnt sound like an issue its supposed to unlock when there is a load put on it like that. mine does it just cruising at a constant speed on flat ground. and speed
 
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