Alright, so I have been playing with this for a while. Was doing some mudding in my 98 expedition, and lost 3rd and 4th gear, the trans feels great except will not shift up past 2nd. I put it on the lift, dropped the pan, had water in it. Put in fresh fluid and a new filter. Didn't fix it. unplugged the solenoid connector and it was starting in a too high gear, which leads me to believe the solenoids are working, and it is capable of the higher gears. No grinding, and the fluid was free of debris, and the 1st to 2nd shift feels real good. Now I am checking the mlps, and can't find a pinout for this year. It is a 12 pin not the old 8 pin. Also, did this year have a dtr or the analog mlps? Any ideas? thanks

 

Here is a pin out chart for a 4r70w range sensor in a 98 Expedition.

I would use a scanner and watch the data stream to check the MLPS switch.

I am unsure on exactly how to check this with a volt meter, I think you will have to watch the voltage on the signal return wire. The voltage will change in the different gears. I do not have those values right now, I would just make sure the voltage is different from 2nd to 3rd and 4th.I have never done this test this way but it should help you make a educated guess.

I have included a wire diagram so you can see how this system works.