I have a 92 F250 with a 7.3 4x4 diesel and A4OD tranny. Recently the tranny seems to have a problem staying in overdrive. My past experience with a different truck that lost it's overdrive gear was that soon after the overdrive started slipping, it would just stop working and going into it completely. With this truck, it seems to go in and out of overdrive, then will stay in it for a period of time and then once in a while will start shifting in and out again. This will happen at highway speeds of 60mph and back road speeds of 45mph driving at a steady speed. I am trying to determine if there is some type of solenoid that may be going bad that shifts the OD gear, or am I really loosing my OD, just has not happened completely yet. Any help would be greatly appreciated. Thanks.

 

I changed the fluid with Dextron lll and a new filter. The old fluid looked good, clean, red.

 

There are a few things that can go wrong with the E4OD and cause your problem. The first thing I'd do is replace the Transmission Range Sensor (TRS.) It's the sensor on the driver's side of the trans with the wiring harness. Some people call it the neutral safety switch. When they start to die they tell the PCM that you moved the shifter to N, so it downshifts the trans.

The next possiblilty is that the fuel injection pump lever (FIPL) sensor is failing. Some people call this the throttle position sensor.

It's probably not a solenoid because the solenoids are multiplexed, so if one goes bad you lose more than one gear.

 

thank you, I will take a look at both.

 

I looked at both sensors. The tranny sensor still looks good. I removed the connector and cleaned it with cleaner and compressed air. The throttle sensor looks pretty bad. I have a spare on a spare pump. I will try to swap that one, but the torx bolts look like they have been stripped by someone trying to play with this sensor before. I will post any results. Thanks again.

 

The TRS will look great even after it's dead. The failure is inside whare you can't see it. If it is the original sensor CHANGE IT, either now, or after it destroys your transmission. If you leave it on long enough that all those shifts require a rebuild, make sure you put a new TRS on the new trans so it doesn't trash that one, too.

 

Thanks Mark, I will see where I can find one tomorrow.

 

I was able to get a new neutral safety switch and am trying to install it. As I was removing the old one, the shaft on which it sits came out of the tranny by @ 1/4". I do not want to just force something back in. It will not just go back in. Is there a procedure to push that shaft back into the body? Do I need to drop the pan to see what is happening an how to get it back in? I am trying to see if I can do something without dropping the pan as that would require another trip to the parts store for more fluid. Thanks.

 

That shaft should not come out. There's something wrong.

 

I would not say it came out, it seems to have moved out by @ 1/4 ". The reason I say that is because the shaft end right by the tranny is very clean and shiny as if it had been in the tranny previously and when I put the new neutral safety switch on the shaft the stand offs do not reach the tranny by about the same distance. Do you think the only option at this point is to drop the pan and see what happened? Thanks.

 

Does the new TRS look like the old one? If it is, and it won't go flush to the mounts, something is wrong and the pan will have to come off to find out what happened.

The shaft will be shiny where the old sensor was riding on it.

 

I took the pan off. The pin that holds the rod in place was out and the rod was lose. When I pulled on it to get the old sensor off the rod pulled out and came off the spring clip that keeps it in gear. I was not able to push it back in because it was pressing against the outside od the spring clip. I put everything back in including the pin. Will test it out later as I have to pick up some fluid now. Thanks for all your help.

 

It looks like that was the problem. One more question. How much can I tow or pull with this transmission in Overdrive? I never pull ot tow anything heavy for a very long distance (usually no more then 5 miles) so I always disengage the OD when doing so, but if I ever had to pull something long distance, what woul be the maximum safe load that would not damage the OD and the tranny? Thanks.

 

You won't damage anything if you turn off the overdrive if it starts searching for a gear. If it stays in overdrive it's fine.

 

you are saying then that if I put too much weight on it then it will start switching in/out of OD. At this time I will just have to take it out of OD manualy and run in 3rd gear. As long as it stays in OD, then everything is fine. Is that how I should understand it? Thanks.