hey guys, new to the forum and i got a problem..... isn't that always the case


this is a long story so bare with me. so i just bought a 96 f-250 with 7.3l turbo diesel with a e4od transmission. its my first diesel and also my first automatic. anyway, when i bought the truck and test drove it, it was shifting hard, he told me it was because it had a "built" trans with a shift kit....... shows my lack of knowledge on automatics...... its very much stock with many miles.

either way i bought the truck and drove it around thinking it was fine. well last weekend i was pulling a trailer with the truck and blew the front seal in the trans. replaced that and came to the conclusion that maybe something was wrong with it..... i started looking around at causes to the hard shifting. came to the conclusion that it was a lack of voltage to solenoids. i fixed a few wires that looked questionable in the charging system and had the alternator tested. well after having the battery disconnected for a little while, the trans started shifting flawlessly .......... well next day it went back to shifting rough and the overdrive light started flashing ..... however that did reassure my belief that it was electrical and not mechanical

so i started looking for more things that could be robbing power. replaced a few more more questionable wires and cleaned contacts in plugs to the trans, but same story, shifted fine for a day then back to the problem.

so today i went up to the parts store and had them test my batteries, one battery was junk and the other was on its way out. so i got two brand new batteries drove around all day and it seemed my problem was solved until it hit again, rough shifts, and overdrive light. so i disconnected the battery and now its shifting fine again.

iv replaced the map sensor as well. code reader wont bring up any codes even though the overdrive light is flashing.

WHAT could it be? its very random, happens when cold or hot, itll happen when i take it easy or when i floor it. i cant find any connection in order to predict when itll go bad. once it starts to shift rough its rough in every gear and wont use overdrive. and it doesnt go away until i disconnect the battery and reconnect.

any suggestions on what i should try next?

thanks in advance.

 

Check for codes. Always the first thing to do. Even if the check engine light is not on there could be codes. And I the OF light is flashing there should be a code.

The reason it works for a bit when you disconnect the battery is it resets the limp mode in the transmission. After a bit it goes back into limp mode again

 

Just realized you said you did check for codes.

 

Right. Any obd2 reader should show transmission codes, am I right? Iv tried a couple times and there's never a code found. It would make my life easier of it would show a code so at least I'd get a better idea.

 

No, you need to take it to a transmission shop to get the codes.

 

try replacing the big metal fuses in fuse box

 

Also my abs light is on. Does anyone know if that would effect trans performance?

Any particular one of those metal fuses or just do them all?

 

Hows your speedometer? Is it jumpy?

 

No the speedo works well. All the gauges read well. Only things to speak of on the dash are the abs light and the overdrive light when it decides to act up.

 

Do they blow or just fail on their own?

 

after you drive it see if the fuse is really hot if so replace it

 

YES it will. at the back of the truck behind the bumper up near the inside of the drivers side frame is 2 sets of wire plugs, they feed the tail lights. if either of them is dirty or has a poor conections the ABS light will come on and that will definetly cause the trans to go into limp mode. My ext cab had broken locking tabs on the plugs and they constantly came loose and made it shift bad. take a look at them, spray some WD-40 in them to clean em out.

A bad ICP conection will cause bad shifting too, but they idle funny when that happens, if the idle is good I wouldn't look at that.

Diesel Rod

 

Awesome I'll definitely check out those connections. Especially because it seems to occur almost immediately when I plug in the wires for my trailer lights.

I doesn't idle funny but what's the ICP? I'll check it anyway

 

ICP, Injection Control Pressure, its a sensor on the head that senses the high pressure oil feeding the injectors, but like I said if it idles fine, don't worry about it.

Does it do this when there is no trailer? if so then the problem is in the trailer wiring.

Diesel Rod

 

96 the PCM gets is speed signal from the ABS system. It sounds like the EPC is stuck at full pressure, however, limp mode on an E4OD will do that. Ford decided it was smarter to run max pressure to save things in the transmission. If you lose the power to the solenoid pack, full limp mode is 4th gear only in any forward range.

Ohio, you're a little far away, I have a Rotunda transmission tester if you were closer.