O/D light blinking Transmission Shop can't read codes

[H-manz]

I've got a 95 XLT 4.0 OHV 4x2, and the O/D light is blinking and it won't shift into overdrive. It didn't start flashing the O/D off light until one day when I was pulling a trailer with only a push lawn mower in it. (nothing heavy) I figured that connecting the trailer to the plug that supplies info to the trailer (brake lights, blinker, etc.) had caused the computer to get squirly since it had never towed anything in its entire life. (this was about a year ago) Also, I should note that I went up in tire size from stock size to the maximum size the truck could have,( without any lift or suspension modifications), without rubbing any while turning. I put on some expensive BF Goodrich A/T baja champion II to give it a much more pleasing aggressive look to it while also giving a slight but noticeable height increase. Didn't have any issues immediately after the swap with the tires. But no one at the Tire shop told me about the speedometer being off after such a modification. It didn't even cross my mind (I was about 19 with minimal experience with cars at the time) that the computer calculated speed by RPM of the wheels, and that it would be affected by an increase in tire size. Come, to find out my speedo was reading about 7 MPH too slow at 70 MPH (speedo would read 63 when I was actually doing 70) once I figured out this issue I looked into it and found that I had the model where I could simply change a small plastic gear at the end of the speedo cable that goes into the transfer case with a gear with one less tooth on it and it got my speedo back to being right on. I was hopeful that this would help my transmission issues since the computer would now know the actual speed I was going and would be able to correctly calculate shift points etc. But my hope was in vein. It still flashed and started to hard shift and still no overdrive. Even after unplugging the Battery letting the computer reset and trying again. The O/D light will not blink when I drive around town and it will shift smoothly with absolutely no signs of any trouble. But as soon as I get going about 45+ mph The light will start to blink and the issues will start again. I checked transmission fluid and it was not looking too good and it was low. So I added just a small amount until it was at the correct level while at operating temperature and in neutral. I have noticed that the bottom of the transmission there is a slick film over it that is apparently a leak of some sort but it must be a very minute one as the transmission fluid was not too much lower than it shouldv'e been. Seeing that the issue wasn't something that I believed was in my capability range of mechanical "know how" I took it to the most promising transmission shop in my area that wasn't a ford authorized dealership/mechanic. They have had it for 2 whole days and haven't even dropped the pan on the transmission. I was infuriated by this and they said it was because they cannot "communicate" with the truck (i.e. get it to give them any transmission codes, or any codes at all) but they said that if they couldn't get any by this afternoon that they would just tear into the transmission and try to figure out whats going on that way. Anyone here have any suggestions on why they can't read the tranny codes, or what could be wrong with the transmission, does it have to do with the larger tires, is this a common issue, i've got a million questions that I figured a TRANSMISSION SHOP would be able to answer but I haven't gotten a single one, very frustrating.

 

[Mitchs07explorer]

If you've only gone to the one shop then go try another and see if another shop or auto parts store code reader can read the code. Also check out the "Gen 2 issues" sticky thread on the 95-01 forum, that thread has a bunch of links to help fix common problem issues with that model. I wonder if your electronic connections are fouled and that may be what's giving you issues, check this thread out.
2nd gen issues? Try this first!

 

[Mr. Alligator]

In my experience, most transmission shops only want to install new or rebuilt transmissions. A few transmission shops actually rebuilt transmissions, or are willing to install asalvage transmissions, but I have never found a transmission shop that repaired transmissions.

Also, my 1997 4.0 SOHC PCM had electronic issues a few years ago, and had symptoms similar to yours. Most transmission shops did not even check for codes, and the one that did said that no codes were available. After thst shop installed two different salvage transmissions and each of the transmissions had exactly the same "problem", it was correctly determined that the fairly simple PCM replacement was necessary, and solved the problem.

Good luck!

 

[toypaseo]

Dunno if this is related, but I had a co-worker with similar problems with her mid-late 90's 2WD Ranger. A local mechanic traced her problem to a broken (missing?) clip to a cable that goes to the transmission. The clip holds the cable into the transmission. They could not source a replacement. They just temporarily repaired it with some silicone sealant. The problem still shows up, but not nearly as frequent.

 

[96eb96]

95 needs an older scan tool or flashing codes by jumping a wire. Assuming the computer is ok it sounds like a broken band or bad servo sleeve. They can remove the overdrive servo near the cat converter, there are kits to repair it. The bore inside gets worn, the servo binds up, sometimes it snaps the band, sometimes you can get a repair servo, sometimes not.

If the band is broken, you have no overdrive, it has to be rebuilt, common failure, that actually made the 2002 Explorers the worst truck to buy because the metal in the hole was softer and sure to fail. Make sure they sleeve the bores. Possible the trailer or larger tires stressed it out but age is a factor too. It is 24 years old....that trans owes you nothing.