More tansmission problems torque converter lockup

[cowman79]

So I installed a different solenoid pack in my transmission about a month ago and all seemed well. The truck drove great for a couple of weeks then one day I left the house and the truck locked and unlocked the torque converter about five times and then locked up and acted normal the rest of the day. Now I am having to drive the truck for about 15 miles before the torque converter is locking up. When the truck starts locking up it seems to work until I shut the truck off and restart and then you have to drive it some more before it will lock in and act normally again. The question now is what should I look at next? I am not getting a flashing overdrive light so I am not throwing any codes. My speedometer is working normal and about a month ago I checked the voltage on my FIPL and it was good no dead spots that I could see. I am really at my wits end with this truck.

 

[PackRat239]

Dunno if I am way out in left field here, but it might be temp related, meaning some trans wont lock convertor until engine reaches certain operating temp to help it warm up faster. I know Mopar and GM do this.

PR

 

[cowman79]

That is what I thought the first time it happened. But now the trans temperature has been 130 degrees before it will lock in but it isnt always consitent. The first time it happened the transmission was about 70 degrees.

 

[PackRat239]

I think it is the engine temp that controls the lock up, not the trans temp. What is that doing?

 

[cowman79]

The engine temp is normal.

 

[FORDF250HDXLT]

you replaced the pack due having a bad seal and had fluid in the connector iirc or was this someone else?
if this was you,did you spray the connector out very good with electrical cleaner before plugging it into the replacement pack?
there is trans sensor on the pack as well,but there is no connection from the engines temp sensor to the trans ecm at all.

 

[cowman79]

Yes that was me. When I swapped it out it had fluid inside and I was having problems with the truck shifting early and torque converter not locking up. I didn't spray the connector out buy cleaned it as good as possible.

 

[LCAM-01XA]

Cowman, the fact that you ain't getting codes don't mean the TFT ain't bad. Matter of fact what you're seeing is exactly what I saw when I bypassed the TFT altogether w/ a fixed resistor in an attempt to to fool the TCM that transmission is always cold (so it would never command a lockup and I could use my manual switch as I please w/o throwing code 62) - trick works initially, but that evil thing is just too smart for its own good and after good 10-15 min of driving it would ignore the TFT signal altogether and default to its regular shift schedule, lockup and all. Point is, if the TFT somehow managed to fail in a "cold" but legit position (such as 30,000 ohms, which corresponds to 75-80F) then you won't see any codes for it (at least I didn't) but it will take a good long drive for the PCM to eventually ignore it and give you lockup back. And this cycle will happen every time you shut truck off and restart it again, regardless of actual fluid temperature. On the flip side if your TFT failed in a "hot" and again legit position (say 5000 ohm, which is around 160F) then you'll be code-free again and this time you'll have your lockup available from the get go, even when the trans is actually still way too cold (tried and verified w/ almost a full oil change interval on a 4700 ohm resistor fixing temp at 175F or so).

So yeah, drive truck around for a bit to warm the trans up (or leave her idling in drive w/ parking brake on for about 5-10 min), then shut her off, disconnect the trans harness connector under the brake master cylinder, break out the DVM and get to measuring some TFT resistance! I posted the color coding for the wires needed in your last thread IIRC. Sorry if I sound like a broken record there, but w/o knowing what signal the TCM sees you can't really try to explain its behavior.

Do spray some carb cleaner up the trans harness connector for the solenoid pack tho, and air-blow it dry - ATF ain't exactly the best electro-conducting media known to mankind, so if some eventually found its way into the pins for the TFT sensor wiring it may be jacking up the overall resistance of the circuit, which to the TCM means cold trans and therefore no lockup till sensor reading is ignored.

 

[cowman79]

Thanks for the info. After your first post I started thinking maybe I need to check the connector again on the transmission. Well it was a good thing I did. I found a small amount of oil and some water. It appears that their isn't a gasket in the connector for the transmission and with the rain and snow around here lately the moisture made its way in. So I used contact cleaner and canned air to clean the connector. After cleaning I used vaseline as a water barrier and drove the truck home. The truck acted just like it should locking up at around 35 or 40 mph. Thanks again for all of the help. I guess I need to look inside my old solenoid pack and see if there is a gasket to keep water out of the connector.

 

[Kevin 007]

I vote for a speed sensor issue. If you speedo is "fluttering" at all it WILL cause your TC to do this. Not saying its the only thing to cause it but it is a possibility.

 

[cowman79]

Thats one thing I've haven't had trouble with yet is the speedometer fluttering.

 

[LCAM-01XA]

I guess I need to look inside my old solenoid pack and see if there is a gasket to keep water out of the connector.

Do that - there should be a rubber o-ring type gasket between the male end of the trans harness connector and the female end of the solenoid pack, IIRC it's orange in color. Probably got stuck to the old solenoid pack, happened to me too while installing my shift kit a while back. Carefully pull it out of the old pack connector, clean it real good, then slide it onto the male end for the trans harness, and carefully plug harness back in solenoid pack. Good call on the vaseline, use it on the o-ring too before reconnecting harness to pack, it's a tight fit and she may try to roll on you.

 

[cowman79]

I looked at the old solenoid pack that I just changed out has an Oring made into the plastic. For now I am going to use the vaseline until I get time to work on it again. Hopefully the transmission works good for a while because I am about ready to dump the idi