i have a 91 super duty 2 wheel drive with 7.3 and a4od trans i just replaced the front seal due to a large leak that started leaking with out me knowing and ran the tranny almost dry before i noticed anything .replaced seal new filter and oil . no leaks but now tranny wont work unless i turn off od button .it wants to move but it doest and if you put it in low or 2nd it works but soon as you go to drive it acts like its in n if you push button to off it goes into 3rd perfect .i have checked all connections and did a omm test on solenoids and everything checks out fine .it has not set any codes and light is not or has not blinked since this started doing this.any body have any clues where i should look for problems ? i have no idea what caused the front seal to start leaking this tranny was rebuilt approx 80000 miles ago and i don't know what converter is in it or what up grades were done. also after you stop and put in p and turn off motor you can hear something spinning for a few secs than it stops and it never did that before . thanks for any help i just don't want to go get ripped off foe tranny rebuild and it doesn't really need it.

 

Have you checked the wiring harness near the transmission?

Its possible the transmission overheated and melted some of the wires.

 

the wires looked ok. do you know of anyway to see if the computer is working ok ?and do you know where it is located ? i checked the fuse and its getting power there . will it still work at all if its not getting info from computer ?

 

With no 12v power to the transmission, you should get 4th gear with the gear selector in Drive, second gear with the selector in "2" or "1", and reverse, torque converter lock up will not work. To really test this, You could unplug the transmission from the electrical, and run it with the wheels raised on jack stands. I did this several times when troubleshooting mine.

Engagement from neutral or park to reverse or forward will feel more rough, and engine RPM will be more taxed.

I think the computer is located below the brake booster on the firewall. Some one please correct me if I am wrong. I ran an aftermarket PCM from day 1, so I'm not positive of the location of the OEM computer.

 

If the ecm wernt talking to your trans you would have two forward speds and it would shift really hard and probly not untill the tranies govorner rpm I think its 3200rpm.

 

you have internal damage it sounds like the o/d input one way clutch has been damaged or thr forward clutch is damaged , when you shift into 2 nd or low the transmission boosts line pressure and also applies the coast clutch
the coast clutch is also applied when the o/d switch is cancelled which overrides the input one way clutch
a massive leak at the front seal usually means the transmission overheated and this is usually because the torque converter clutch is slipping or not applying
and if your truck still has the original transmission processor it does not have the ability to flash the o/d light when there are malfunction codes in the pcm
this feature didnt go into production until 92

 

Ford transtech Could you pleas look at this thread and tell me what you think is going on. I would grately aprietiate your input.

https://www.ford-trucks.com/forums/7...m-tc-lock.html

 

thanks for everyones help but thats what i didn't want hear..but i figured it had to be major. anyone know anybody in so Calif around orange county area that does a good job on these ? is it to costly to go manual tranny ? any other choice i have ?. it doesn't seem like its very smart to put alot of money in this old truck when diesel fuel is almost 5.00 per gal. it still runs great and i use it for a work truck every day doing concrete work so maybe its still better than anything else. i need to do something asap. thanks again ken

 

could you tell me if a auto tranny from a 1994 would work the same without any changes.? its out of the same kind of truck i just dont know when all of the stuff changed or will it just bolt in and work . thanks again ken

 

It'll work if the truck has an IDI 7.3 and if it has a powerstroke I'm pretty sure it will still work.

 

no because the 92 up did not use a vehicle speed sensor in the transmission and the drive gear for it was machined into the output shaft and eliminated
but you could remove the plug for the vss sensor on the 94 trans and see if by chance it does have the gear made into the output shaft
if it does you use your sensor and it is a bolt in proposition

 

Sorry, didn't mean to get your hops up.

 

is the vss sensor in the tail shaft only ? could i just swap tail shaft pc from the 91 to the 94 ? or is there more to it .

 

from what ford trans tech said the the hole to put the sensor in is still there but the drive gear may or may not be macined into the tail shaft of the new trans.

 

yeah thats why i was wondering if it was possible to swap the tail shafts from each other that would take the guess out of it unless i dont understand what he means.