Hey everyone, so I was hauling a trailer this morning with my 2002 F-250 7.3 diesel. Going down the highway apparently my transmission overheated and all the fluid came out thus leaving me stranded on side of road. It was towed to local shop and they put more transmission fluid in and were able to drive it. The codes p0743 and P0741 came up. They trying to tell me I need a new transmission. Aren't those codes for the clutch converter and a solenoid?? It's tough because I need this truck back up and running asap! Anyone have experience with this?

thanks!

 

Good morning Heath, and welcome to FTE!

I'm guessing we're seeing the cause, the effect, and the final result here. Cause is the P0743 circuit failure that prevented the torque converter from locking when on the highway. The PCM saw that the converter wasn't locking when it was telling it to(the effect), and set the P0741 code. The final result was the overheat caused by the unlocked converter, which puts a tremendous amount of heat into the transmission.

Most likely the leak is the front seal of the transmission, which can get soft and leak when it gets hot. Very common for this to happen when backing a trailer up a hill, but towing with an unlocked converter could do that as well. There's a good chance it'll seal up now that it's cooled down and not trouble you again, but it may need to be replaced.

The real question is what damage was caused by the overheat? I'd suggest troubleshooting the converter clutch circuit failure, flushing all the transmission fluid, and seeing how it drives.

 

as above stated.

15 year old truck.

when working hard.. transmission fluid and filter should be changed every 30,000 miles HAS IT??
if not working hard, every 50,000 miles.

old, tired fluid is BAD.. just like motor oil..

You do not offer mileage.. did it wear out????

but overheating is Bad,, and total loss of fluid is Bad... a double bad.

 

My take on this is the P0743 code is from the root cause of your problem. That code sets when there is an electrical circuit error in the converter clutch solenoid circuit. It could be a bad solenoid or a damaged wire between the PCM and the solenoid. It takes some hands on diagnostics to determine when one is the problem.

The P1741 just says the converter didn't lock when the PCM wanted it locked. That's a result of the electrical problem. The overheating is a result of the converter clutch not locking.

So if you find and fix the electrical problem everything should be fine, unless the overheat was so severe it damaged the trans. And that takes well over 300°F to accomplish.

A new trans might fix this. The electrical problem could be outside of the trans. You could just have a damaged wire.

 

Thank you Tom and Chuck for replying!
I have only owned the truck for a little over a year and have only put about 10k miles on it but most of that has been mountain driving. But no, I haven't changed the filter or changed the fluid. It has 170,000 right now. I had the OD light flash a couple weeks ago after some driving over a mountain pass ( lots of shifting up and down) I tried to have scanned but it was very cold that morning and no major codes came up. It was a heck of a time getting it to scan. Anyway, even before the over heating issues on the highway I never thought it shifted bad. It has always shifted very smooth.

Do you guys think the overheating could have damaged the transmission?

 

Thanks Mark for the insight also, I just saw your post!

 

i just picked up a 99 7.3, 4x4 about 240k miles, unknown history.
i have swapped fuel filter and engine oil but now thinking about the transmission.

what would you guys suggest i do for PM to that?
thanks

 

I suggest this: Changing ATF Fluid in a E4OD and 4R100 transmission - Ford-Trucks.com