I'm really struggling with this one! So I hope someone else out there has had the same issues and can point me in the right direction.

Have a 2002 Ford Explorer Sport Trac 4x4, and when I first got it, it shifted a bit hard but no other issues. Then within a day, the speedometer starting acting really erratic (very quickly going from low-to-high speeds and back even though I didn't change speed), and with it, the transmission was shifting gears, presumably because it thought the RPMs suddenly went high.

Before I could even get it somewhere to looked at though, that devolved into the speedometer just not working at all - it just sits at zero - and I have to manually shift the truck into 2nd in order to get out of 1st. Even then, it seems to be in limp mode, and won't go very fast.

I noticed that a wheel speed sensor had been sheered completely off, so I replaced that, and although it could then shift out of 1st automatically then, the speedometer is still non-functional and the truck still seems to be in limp mode.

Mind you, the Check Engine, Brake, and ABS lights are all on even after clearing the codes after replacing the wheel speed sensor, and the O/D Off light is flashing. This thing's a damn Christmas tree!

AND just recently, I noticed that the RPMs were holding steady at about 3-4k no matter how high or low the engine was actually revving.

So I took it to a mechanic who's saying that Transmission Input Speed Sensor that may address the P0715 would take him 7-8 hours to get to, being internal, but he can get to the Transmission Output Speed Sensor, which may fix the P0720 code. BUT I find it hard to believe that both sensors went out simultaneously, and the P0715 was on for a while before the P0720 showed up.

And now I'm seeing that the P0715 could be related to issues with the PCM and/or wiring, not necessarily just the sensor. So I could potentially drop many hundreds of dollars having a pro take apart the transmission to replace the sensor and still end up with the issue not being resolved.

So has anyone else come across this? I'm not sure if there's anything else I can check for aside from researching reputable transmission shops in the area and hope that they don't try to screw me over.

Oh yeah, and by the way, I found a nest of some sort in the air box, so I know there's been critters living in the damn thing (not sure how long it sat before I bought it). I think I really stepped in it with this thing.