I've got a 99 F350 4x4 V10 that is stuck in 4Low. It was never put in 4low. Started the truck and the transfer case automatically locked it in. It is the electronic shift on the fly. What could be the issue and how do I fix it?

I've checked fuses, not sure where the relays for the shift of the fly system are, so if anyone knows where their located I'd appreciate it. According to the fuse chart they are #40, but there is no #40 location labeled under the hood.

Tried putting it into 4low, 4high, then back into 2 wheel and no luck, still stuck in 4low.

Help!!!

 

I have no idea on how a 99 and my 02 compare but if it were my truck, 4 10 mm bolts and two wire harnesses will get the transfer case motor off the transfer case. Once you get that off grab a wrench and manually put the transfer case back into 4 high.

 

Try backing up for a decent distance and then cycle the switch as you place the trans in neutral and are COASTING backwards. May be bound up

 

Already took the shift motor out and manualy put it back into 2wd.

How can it get bound up, if I never put it into 4low to begin with. The transfer shifted to 4low on its own?

I was working on the truck yesterday, trying out a new generic control module. It wasn't the right one so I put my original back in. Had the battery disconnected while working on it. Hooked everything back up and then left it in the driveway till today. Went to move it today and the transfer was in 4low with the ****/switch on the dash on 2wd.

 

Check to be sure that when you put the 22 prong harness back on the control module that you didn't ground out the prongs. All the right prong needs is a ground source and it will shift by itself all day until repaired.

 

My truck did the same thing. It was the two relays in a separate box next to the fuse box under the hood .Cause one controls to engage and the other one disengages it.

 

which box, there are two boxes next to the fuse panel under the hood that have two relays each?

one runs paralell to the fuse box, and one runs perpendicular to it

 

Checked the relays, and they are good.

Question about the shift motor on the transfer case:

Is it possible to manually turn it back to the 2wd setting or is that not possible?

I've put the truck back in 2wd manually... now I want to put the motor back at the 2wd setting manually as well. I've tried turning it and I can't get it to turn or move at all. Is that because it's not possible to turn it, or cause it's gone bad?

How can I test the shift motor to see if it has truely gone bad?

Does anyone know how to check to make sure the signal is getting to the shift motor? What pins to check on the plugs, what the voltage should be if a signal is coming thru?

 

With the key on, put a test light across the two pins of the two wire connector. There should be no power there until you try to shift. I expect you will find power there, however.

I am making some assumptions, but I suspect you grounded something you shouldn't have when you worked on your GEM. The coils of the two relays have power supplied all the time, and the GEM grounds them to activate the relay and move the shift motor. I expect you have the high to low relay grounded, causing the shift motor to want to move from high to low.

 

make sure the tires arent in a bind like having them turned, put the truck in N and make sure it will roll smoothly, then push the brake and hold it, turn the **** to 4H or 2wd and while keeping your foot on the brake wait a few seconds and you should hear the motor disengage the tcase. The electric shift is not suppose to move unless the truck is in N or P and the brake is being applied. My dad does this all the time on his 2000 diesel and calls all the time asking why it wont go in or out of 4wd.

 

when you get it fixed you should use the 4wd at least twice a month, click it in 4H going down a 25mph street, if your in the back yard a dirt lane anything put in in 4L just to keep the motor moving to keep it freed up. I do this at least twice a month and havent had any problem so far. knock on wood