2003 c320 4matic.

Background. We're in the middle of a cold snap, when it's cold like this the 722.6 transmission leaks a small amount of fluid from the 13pin connector. I gather this is a fairly common problem. I've had the replacement bushing and O rings around for awhile and figured now is as good a time as any to change it.

Before beginning this repair the car ran and shifted with no issues. Repair went fine. Followed the standard procedure. The new bushing and Orings pushed in fine, tight but fine. It pushed in to its final proper position and 7mm bolt was able to be tightened without issue. Connector was inserted into the new bushing and when the lock ring was twisted clockwise the connector pulled in as you would expect to its final position.

I lost a fair amount of fluid when I pulled the connector out and I'm not sure how much has been lost with it leaking lately so I had to take an educated guess on how much to refill. Once vehicle was started I took the vehicle for a spin, drove fine for about 1min, shifted up to second once, downshifted to first a then won't come out of first now. CEL came on and shows P0743 "Torque Converter Clutch Circuit Electrical". I can clear the code but it remains stuck in first, gears can not be selected manually, S/W switch does nothing. I'm guessing "limp" mode? I crawled underneath, pulled out connector, sprayed it out with contact cleaner, dried it off and reinstalled, same issue. I can clear the CEL, but once the car is turned off and back on again it comes back. I'm guessing there's a code "stuck" in another module that I can't clear with my cheapo reader that causes it to keep popping up?

It's cold and with it being stuck in 1st I can't get the tranny temp up to 80 to properly check fluid level but I suspect it might be overfilled. Would overfilling cause the P0743 code. Once "limp"mode is engaged is there anyway to get it out of that mode without a more advanced diagnostic tool?

Any advice is greatly appreciated as always!

 

That's what I thought, so even if by pulling it apart, cleaning it and re-installing it I fixed the issue I have no way of knowing, and certainly no way of getting it out of "limp" mode.

As I mentioned it's cold here (-25 Celsius), and I've only got 1st gear so it's hard to get the tranny up to the 80degrees necessary to check the level. At 25 degrees the level is slightly higher than the 25 degree mark on the dip stick but I don't know how accurate that is.

Either way with my inability to clear the code I have no way of knowing if anything I've done or do fixes the issue, so off to an independent shop. Because everything was working top notch before I started this repair I'm hoping it's just a matter of a loose or contaminated connection on that 13 pin connector. I really didn't do anything all that evasive. Connector out, bushing out, bushing in, connector in. Hopefully my brief 1st gear drive with it overfilled didn't take something out? What's the chances?

 

I always try to update a thread when a resolution is found so that anyone in the future reading this may find help, so..........

When I installed the new bushing I somehow managed to catch one of the pins located on the conductor plate, catching that pin slightly bent it so that when I installed the connector itself the pin didn't line up with its female counterpart in the connector and it folded right over. I'm not sure how the whole thing even managed to go together so smoothly with a pin sandwiched in there sideways but that's what happened. When attempting to bend the pin back it un-surprisingly snapped off. New conductor plate was needed and the car is back to its old self.