I've been lurking here and even posted for a few years now. What a great source for helping me with all the little problems that have popped up over the last 4 years.

I will do my best to explain the problem I am having and what I have done so far to eliminate it.

I have a shift solenoid A code when I hook my OBD code reader. Symptoms: When accelerating the transmission tries to shift into second and lurches, kind of like it is trying to shift but doesn't fully engage, OD light flashes and then the engine light comes on. It seems to only happen after the engine and tranny are warmed up. OD on or off it still does it.

This started in the beginning of summer so I have done quite a few things. The first thing was change the fluid and filter. The fluid was surprisingly clean as was the filter. When The transmission shop was in there they changed the Shift solenoid as well. The Code popped up almost right after. A week later I realised there was a leak guess what. The fluid was low! The cooler lines were all corroded so I had the shop change them. Figured I had it solved now but no, the code came back!

I've checked all the wiring for rubbing or broken wires. Unplugged and reconnected it. All seems good.

While I was there I found the transfer case to front axle u joints worn. Replaced the front brake pads and rotors because they were also over due as well as the passenger side coil spring was broken.

Oh, And I also replaced the TPS. Part of my thought process was that it is part of the logic for shifting and I felt that it was giving me issues at low speed like when I was backing up to hook up the trailer.

From everything I have been able to read it is an electrical issue, not a failing transmission. At least I hope it is!

I am getting to my wits end to resolve this. Are there any vacuum lines or anything else that might give the ECM a signal and causing the problem? Could it be a bad shift solenoid was put in to replace my old one?

Any enlightenment will help!

 

I would think so since the issue started after it was changed. New parts fail too.

 

Start with posting the specific DTC.

Realistically, the problem might be any of the following:

Solenoid
Internal harness and bulkhead connector.
Vehicle harness and connectors to transmission and PCM
PCM

 

I might not have been clear. The code was there before which us why i opted to change it when the fluid was done.

 

Is there any truth or validity to flashing the ECM with updated software? Is it something that is done and can make a difference?

 

Sure it can be done, but, unless Ford issued some kind of software update to address your particular issue, it won't matter. You'd have to have your Ford dealer check. It's pretty unlikely that your fault code, whatever it might be, is due to a software issue.

 

That is what I had thought.

Funny thing happened today. I was driving home from work, stopped to get a coffee. On the way it immediately had the shift problem. After going to get the coffee I start up the truck back up to the left and pull away. No shift problem! Also The steering has been a little heavy for a few weeks. I thought it was an alignment problem. It was suddenly gone when I pulled away from the coffee shop! By the time I pulled into the driveway the OD Off light is flashing and it is chugging again. Steering seems to be fixed though! Are the two related? I don't see how but talk about frustrating!

I'll see what its like going to work in the morning.

 

I dropped into a different local transmission shop today and he verified the code that I got and explained that the P0750 code is actually saying that the shift solenoid is working but could not shift when it was suppose to.

He had said he has seen it frequently with this model of transmission. The "Band" goes in the transmission. In his experience they last about 120 000 kms before they go. The previous owner replaced the tranny at about 100 000 kms and I am at 220 000 now. $1500-$2500 to rebuild depending on bad it is when he gets it apart.

Not a happy camper. I really don't have the money to replace the tranny or get a new vehicle.

Feel free to chime in on this.

 

You could always sell it and buy something else.

 

I have a pretty good idea what an 8 year old Expedition with 220 000kms and a blown transmission is worth. Scrap metal is about 12 cents a pound.

 

Go get a second opinion. That explanation has nothing to do with that fault code.

 

Do you think you could expand on this. What is your thought?

 

You could have a bad lead frame in the transmission. That's the hard plastic molded harness that the solenoids plug into. I would try that first especially since you have a solenoid circuit code. I think your tranny guy is looking for work, I have over 200k miles on my original 4r70w with no band problems.

 

What made me second guess the band breaking theory is that I cant find any results when searching for transmission failures!? I am guessing to inspect the hard mounted harness on the transmission i will have to drop the pan and pull out the solenoid pack. First I will try pulling the connector off and look at corrosion with a mirror.

Thanks for the idea. Still looking for more.

 

Hey Gang. I hate when I read a thread and the OP never follows up with the solution and if they ever found it. Well I solved my issue.

I tale to a friend oof a friend who is the transmission specialist at the local Ford dealership. He had some great ideas and things to check out including an interesting pice of info that the 6 speed trannys do not have a band as the transmission shop said it did. Gave me some confidense in what he was saying so I brought it to him and payed $200to have him hook it up to his computer and assess the problem. He traced it to the wire bundle rubbing and wearing through the insulation shorting out on the frame. It was just under the exhaust manifomanifold on the passenger side. He quoted $600 to fix it so being the cheapskate I am I took it home and did it myself. 4 hrs later I reaped the wires and had it all back together. All the connectors had to be disconnecTed un the bundle pulled FWD over the transmissionenough I could get access enough to repair the wires from the wheel well with the inner fender removed. All is perfect now and has never been so good. In fact the stiff steering I was having is solved as well. One of the shorted wires was the transfer case wire which must have locked it causing it to be in 4 wheel high. Steers like it should now.

Anyway, anyone reading this and trying to solve their own transmission problems should consider checking this. I could not see it until I had it apart and pulled out.