2001 EB trans or transfercase?

Hello all. I'm hoping I have come to the right place. I bought a new to me 2001 Expedition Eddie Bauer a few days ago. I knew it would have problems going into it but now I am getting in a little over my head. So I will start at the beginning and go from there.

I got the vehicle home from the purchase and pulled the engine codes. I got P0357, P0442, P0171, P0174, and P0307. I did my research on them and looked into what would be needed. I knew the 442 was most likely the gas gap, especially since the cap that it currently had didn't correctly click. I was right and a new gas cap fixed that problem. The P0171 and P0174 were also an easy fix. I figured it was most likely a dirty MAF sensor and I turned out to be right. While I was at the parts store buying the cleaner, I picked up an air filter too. I figured it was just safer to change the filter out and start my own routine. Turns out the codes were created because there was no filter and so that is why the MAF sensor was dirty. The P0357 and P0307 were both about cylinder #7 having a misfire issue. I lucked out here and only had to replace the boot for 5 bucks. So now all of my engine codes are cleared. Yay, go me!!!!

I have also replaced the engine oil, added some transmission fluid as it was low, replaced the fuel filter, and changed out the differential fluid. Next on my list is a transfer case fluid change.

So here are the major issues.

I can't select a 4x4 mode without blowing the fuse for my backlight on the instrument panel.

Putting the truck into any mode other than 4H results in 4x4 light being on but then not being able to drive forward.

Having truck in 4H mode results in being able to reverse but not more than at an idle speed, however the truck will drive forward just fine. The 4x4 light does not currently come on in this mode.

In A4WD it reverses better, but slips while trying to go forward. The truck just won't move forward.

I am assuming spinning the knob all the way to the left is A4WD and to the right is 4L. I don't actually know as I am missing the knob and have to use some pliers to turn it.

The wife noticed while I was cycling through the gears while filling the trans fluid that switching gears had a loud clunk sound, like a binding sound. Almost like when a brake pad sticks.

I also can't get the gear selector to go low enough to get the truck into first gear.

I don't know if any of this is related or if it is all related. I am just looking for anybody that could by chance point me in the right direction of what I need to look at.

Thanks

So here is a little update. Don't know if it would help diagnose it at all. I went and tested the voltages I was getting at my 4x4 selector switch. From what I had read, you should get about 1V for 4L, 2V for 4H, and 3V for A4WD. That is not at all what I am getting.

I believe this should be the reading for 4L



I believe this should be the reading for 4H

I believe this should be the reading for A4WD


Can anyone verify that my assumed readings are correct? Could anyone tell me why what I think is 4H is getting almost 12 and what I think is 4L is getting almost nothing at all?

If the selector isn't sending the right signal out to the transfer case on how to switch the gears, would that cause my issues of why I can reverse better in one 4x4 mode and not go forward and go forward great in another but not reverse?

wiring diagrams Check the selector switch for the correct resistance values

I can't get a resistance reading from the switch in any setting. I can get a beep telling me there is continuity in one setting but when I switch the meter to tell me the resistance, there is no reading. So I guess this means the switch is bad but could it be bad because the one setting is sending in the 11.2V? Also since that is so high, would that be what is causing the dash backlight fuse to pop?

This was copied from the Manual Sorry pics didn't copy but really not needed

B6 CHECK THE MODE SWITCH




Mode Switch C230

Rotate the mode switch to the A4WD, 4H, and 4L positions.


Measure the resistance between mode switch terminals 2 and 3 while rotating the mode switch through all switch positions; refer to the following chart.

• 
  Mode Switch Position Resistance Range
  A4WD 3,700-4,100
  4WD HIGH 1,040-1,160
  4WD LOW 340-380

• Are the resistances within specification?

Yes
GO to B7 .

No
INSTALL a new mode switch. CLEAR the DTCs. TEST the system for normal operation.

Ok, knowing to use pins 2 and 3 made all the difference. The switch checks out fine.

Still doesn't explain why the dash backlight fuse pops when I turn the switch and why I don't have the 4x4 light illuminated on the dash when I am in 4H. At least I know one thing works.

Have you looked under the expy at the wiring harness that is under the drivers seat and goes to the transfer case. I ask that because on my 01 when I brought it the 4X4 wasn't working and I found that the harness had about 7 or 8 broken wires May not be your problem but its worth taking a visual check

Can you tell me which fuse is blowing The # and which fuse box it is in

Ok, I put the switch back in but pulled fuse 18 so I didn't blow it again as I messed with the switch. For some reason I can put my switch into four positions. If I turn it left past the A4WD, it puts the truck into 4L. You can hear the motor move everything in the transfer case into place. You can then move it back to A4WD and hear stuff move back.

I put the truck in each 4WD mode and reversed straight back and then moved straight back forward into my park space. Driving forward works just fine in each mode. Driving in reverse does not work fine in each mode. My initial diagnosis of this was wrong. Now, there is a lot of jerk when I switch from reverse to drive or drive to reverse. The truck lurches when the gear kicks in.

I guess this leaves me with a transmission issue only and some kind of electrical problem for the fuse. I suppose that is a lot better than where I thought I was.