I did indeed search the forum and found a lot of useful info, so this is not just out of the blue.

My 94 F350 turbo deisel with the E4OD tranny is hard shifting now between first and second. It all started a few days ago when I noticed the tach not doing right. It was like it was trying to settle in between gears while running 50-60mph on the freeway, almost like a manual tranny slipping but I wasn't losing any power, just like it was searching for a gear.

Before that, Overdrive light blinked only when idling or decelerating, and the tach just sat at zero when idling. I figured this was normal, apparently not. So once the tach started jumping all over the place a few days ago and the transmission started acting funny, I did a search here and found it is in "limp mode" I suppose. Having no code reader, and not being able to run to a parts shop or dealer in the truck any time soon, I replaced the tach sensor hoping that somehow it would magically fix my problem. Well, the tach works fine now, and I didn't get the jumpy tranny trying to settle into a gear at 50 mph on my short test run this eve. I'll know more how this worked tomorrow after I run 30 miles to work in the morning.

But now the OD light flashes constantly and it still hard shifts from one to two and two to three is a littl rough as well. I pulled the speed sensor on the rear differential and it seemed fine, although I don't know what to look for really. My positive battery cable was recently replaced with a new starter as well, and I am having fits with this truck with all the little money draining fixes.

So, any idea on what to do next short of the proverbial "get a tranny overhaul"?
I can't justify a new transmission with all the damned money I'm sinking into it, I'm just out of funds altogether on it, and more engine work is likely coming soon with my prior problems.

Can any transmission experts chime in here? I'm getting frustrated with this truck

 

I am trying to track down similar problems, have you checked the voltage to the FIPL sensor on the IP? They can come loose and be off or it may just need replaced. That sensor and the VSS sensor is what regulates how the tranny shifts and I would think that one of them is causing your problem. You have to set the voltage to about 1.1 volts off of the grey wire with the white stripe. I am usure whether the grey/white wire is supposed to be a ground or positive though. Mine is showing over 12 volts and the wire is grounded, my tach is also not working at all and I cannot figure out why. This is also becoming frustrating for me as I do not have a wiring schematic and cannot figure out where all of these wires run to. I have replaced my tach sensor, FIPL sensor and the voltage regulator, good luck! I could use some help too if anyone has any suggestions.

 

Thanks for the reply. No, I haven't checked anything voltage-wise since I don't have a meter. I'm pretty much a newbie to working on vehicles, but that's changing as this truck tests my patience. I did a search and read about the FIPL sensor many times, but I don't know how to locate it in the trck (again, so new to this I don't even have a manual or Hayes book yet). I have both batteries disconnected at the moment to purge the codes from the computer, someone mentioned in a thread here before that if I fix the tach sensor issue that the code will still be there for 40 key cycles, but that clearing the codes can be done by reading them or disconnecting the power to the vehicle fo a while. My truck is still in limp mode, gonna see if the clearing of codes will bring it out, then we'll go from there.

 

OK, after clearing the codes everything works fine, tranny doesn't hard shift, tach works with the new sensor, OD light doesn't flash. Back to normal. Now to wait and see if it starts acting up again, I'll give it a week/maybe 300 miles to throw a new code if the problem is present elsewhere (as in not the tach sensor alone).

Now, off to locate my power steering fluid leak...

 

I had this problem with my 1994 F350 7.3 TDSL just a week ago. First make sure that your TPS (Throttle Position Sensor) is operating correctly. Autozone sells books to help you diagnose and test the TPS. The TPS lets the transmission know when to shift. If this code comes on the transmission will shift hard and will make your OD light shift on/off. IF the TPS is correct operating order, then the torque converter is bad. It was in my case. They have a bad history of going bad. Sometimes you can repair it without replacing it. You will need to remove the inspection plate between the transmission and the engine. Tap the starter until the drain plug on the torque converter is aiming down. Drain it and replace the transmission filter while you are there. Refill it and hope it works. If it doesn't, you will need to replace the torque converter. Get the one from the dealer. It is heavier duty than aftermarket ones. Trust me you only want to replace it once. It cost about $240.00.

 

For whatever its worth I have this tranny, and it is not a good trannsmission. i am planning on putting a stanard in it soon. I had the same problem with mine that started after pulling a heavy load of hay about 4 months ago(probably to heavy for the whole truck 22 or 23 thousand pounds. My solution, drive it hard shiftying for about 3 months with the light blinking thinking how much I wanted a ZF and that I would have to replace it soon, then one day after becoming tired of the jerking around, I went in to a Manny, Moe and Mack and bought a 3or 4 dollar bottle of tranny repair miracle magic fix all and poured it in and you'll never believe it it but it acually worked! That never happens for me anyway. My theory is that the fluid was worn out and this stuff just rejuvinated it, but who the hell Knows, as I said for what ever its worth.
Good Luck