1993 F-250, 351W E4OD trans.

When I put the truck in 'D', it struggles to go forward. Honestly it feels like I am power braking. However, if I drop the selector to 2 or 1 things seem to work as expected. I can also shift to 'D' once I'm up to speed and all seems OK.

I also noticed that the OD light is not working. This made me wonder if perhaps something electronic is broken and perhaps the truck is trying to start off in OD when D is selected. I pulled the plastic cover on the steering column and inspected wires from OD cancel button that are known to wear/short. All not only looked OK but tested good (continuity). I also checked fuse 17 which can blow in this situation (mine was fine).

Anyone have further thoughts? Thanks in advance.

 

On the throttle body there are two cables--one is the throttle, the other controls the transmission. If the little clip that holes that tranny cable on comes off, the transmission doesn't work right. If you drive on it that way, you can cook the transmission pretty quickly. I've had mine pop off once or twice. Just pop it back on and it should be good to go.

Let me know how that turns out.

Cheers

 

That would be correct if the truck has an AOD transmission. There is no such mechanical connection between the engine and E4OD transmission.

First thing to do for the OP's scenario is pull the codes. With no TCIL light, there is no visual indicator to the operator there may be an issue. I suspect a problem with the connector to the solenoid pack.

 

Starting off in OD is exactly what the E4OD does if it lost its electrical connection to the solenoid pack.

 

Well...at least I got the category of problem right!

 

No worries

 

https://www.ford-trucks.com/forums/1...s-harness.html

 

Update...

I thought for sure it was going to be the well documented electrical connector on the trans. But when I pulled it there was no visual sign of any problem. I was surprised at how good it looked honestly.

Next I attempted to pull codes. No go. Just a solid CEL no matter what I did. I can also hear the fuel pump running any time the ignition is on. These seem to be telltale signs of a bad PCM.

I pulled mine and opened it up. It didn't look too bad but it did look like one capacitor had leaked for sure. Possibly a second and maybe even all 3. They're cheap and I am decent at soldering so I just replaced them all. Unfortunately it does not seem to have made any difference.

While researching where to buy a new PCM, I discovered there are a whole bunch of variations of this thing. Mine had to be replaced about 10 years ago, so I'm pretty sure this is a remanufactured one I have now. Unfortunately, there is barely a trace of the sticker that is usually on the outside of the electrical connector. Someone wrote "818" in this location with a sharpie. There is also a sticker on one of the transistors that reads:

818 8

The '8' by itself might be a 'B', hard to tell. I've included a picture at the bottom of this message.

If I use the details of my truck - 5.8/Federal Emissions/E4OD/GVWR over 8500 - I can see that I need the F2TF-PA variant of the PCM. This seems pretty straightforward.

However - I'm now curious about my current unit. As I mentioned it was replaced ~10 years ago. Is there any way to figure out what version of the board this is? I'm wondering if perhaps it was mismatched. Is that even possible - that is, to have the wrong PCM but have it mostly work? I've seen some weird inconsistencies over the years with regard to CEL, codes, etc.

 

Wow, what a pain.

I needed to move the truck out of my driveway this morning, so I reassembled it just enough to move a few feet. Specifically, I connected the PCM without mounting it back in the kick panel and secured it where it would be OK to back out and park. What do you know, fuel pump shut off after a couple seconds and she started right up. Idled more smoothly than it has in years. Put the selector in 'D' and it worked as it should (not stuck in OD). Thinking I was crazy, I started it again - same deal.

Next I picked up the PCM and looked it over. I decided to try starting again and .. back to square 1. Fuel pump running, rough idle, D stuck in OD, etc.

So my present line of thinking is that it's not the PCM components, but rather the connection - either on the PCM side or the harness from the truck. I don't see any obvious issues like bent pins, corrosion, etc. A few pins look like they may be a tiny bit misaligned but not enough to impact connection to the PCM. One looks to be *slightly* pushed in, but we're talking maybe 1/16". Again, not something I would think impacts the connection. Finally, a few pins are slightly distorted - so instead of round they are a little oblong. One of the first things I did was to inspect the pins and i had to really squint and be pretty particular to see anything unexpected.

Any thoughts? I'm thinking maybe I plug it in and try to get a probe into the back side of the harness so I can test continuity to the pins on the circuit board. Does that seem reasonable? Anyone have thoughts or advice?

 

I would focus attention on the oblong pins. Probably your root cause. Replacement pins...not sure where to get them anymore.

 

Could be the connectors... But I had a Chevy (sorry!) Caprice once that acted similar.. not the shifting, but most all the rest.. it turned out to be the PC Board like you're looking at.. had a "hairline" crack in it.. and if it moved, temps changed etc.. the crack would open and you got dead signal.. the car went into "limp home mode".. once i found it. i could hold it in my hands, gently slightly flex the board.. and make the idle go from good.. to rough.. to good etc! at will. Look it over under a bright light.. at an angle etc etc.. IF.. the connectors don't pan out that is.. you never know.

 

I can find nothing wrong with the connector although it is pretty difficult to truly test. I've decided to order a new PCM from a source where I can return it. I will carefully plug it in and run the truck w/o mounting until I am satisfied it is the solution.

Earlier in this thread, I commented that I needed F2TF-PA version of the PCM. However, I see there is also a F2TF-PB with identical description:

Anyone know the difference? Is PB perhaps a revised version that is compatible, or are they truly 2 different parts that cannot be interchanged?

 

There are minor differences in programming between model years, but if it it's for an E4OD 460, it will work.

 

It is an E4OD but 351w. I found my calibration code: 1076A-R00. I suspect there is a lookup tool around somewhere, I am going to look for that now.

Thanks for the info, please let me know if you know anything about those PCMs and the 351w.

Edit: After searching it appears to me that subford is the man that can cross reference these. Looks like he's been active of late so hopefully he (or someone) will chime in here.

 

Err. sorry, for some reason I thought I read you had a 460. Anyways, the programming is all more or less identical, only minor changes used to address things like emissions, or weird shift behavior, and any 351 E4OD computer will function in any 351 E4OD truck.

Couple of exceptions:

Mass-air 351 E4OD computers will not work, but it's unlikely you'd have gotten one of those

..and Ford made a change to the ignition module around 1993, and the computer has corresponding changes to match. They'll still run with a mismatched ignition module, but might exhibit weird behavior.