I have a 1999 F-250 Super Duty with electronic shift on the fly. I never had any problems with it and one day it quit working. It worked fine prier to that day.

I have checked all fuses they are all fine.

I have tried about everything.

I replaced the GEM module bought it brand new from FORD. I was getting reading then on the computer and a code came up that the 4x4 module was faulting. There was no power coming out of one wire like it was supposed to. I replaced that. Now I got power like im supposed to Still no four wheel drive.

The Electronic shift switch has power to it and works. I have also checked the motor on the transfer case and tested that and works fine.

I called the ford dealer and talked to a mechanic they said they would have done everything I have done so far. My next step it to replace the relays for the 4x4 behind the radio in the truck. I had to order them.

The only code that was coming up now is its saying low voltage to module. I ask the ford dealer they said that could because of an open or broken wire or it could be those relays are bad that im going to replace.

Anyone else have any suggestions because I am out of ideas what to do. The ford dealer and my mechanic are lost to.

 

Today I did some testing... I tested some wires coming off of the GEM module. I have a paper that told me 2 wires to test. It said if I grounded each of these wires (not at the same time) the ESOF should shift into 4x4 high and 4x4 low. When I did that the motor just turned never went into the 4x4. I took the motor off the transfer case. I tore the motor apart and gear box. The small gear that goes on the motor shaft was broke in half.

I have an idea when I replace this shift motor my 4x4 should work. Reason is that I notice there is a switch on the part of the gear casing that slides on the shaft that comes out of the tranfer case. My thinking is that when the motor is turned on to put the truck in 4x4 high or low, it switches that switch whichs tells the truck that its in 4x4 high, low, or 2 wheel drive.

I will let everyone know when I replace the shift motor and gear box if it worked or not.

Anyone else have a problem with a gear breaking in the shift motor gear box?

Hopefully this will help anyone in the future and not have to do what I did.

I spent alot of money replacing parts.

GEM module $460.00
4x4 module $75.00
Shift motor 360.00

That is just parts no labor.... You can not just buy the gear for the shift motor you have to by the whole thing.

 

That's a lot of stuff to go through

Sorry I didn't catch this earlier.

First thing I would have asked is does the 4x4 light come on in the dash? If not, the transfer case is not shifting. At which point I would have said, hook a test light to the two wires going to the servo motor and see if there is any voltage when you first turn the **** to 4x4 with the engine running. If so, I would have said "replace the motor".

 

Do they have that stuff in the wrecking yards?

 

I am having the same problem that dmodracer3 is having. I have checked all the fuses, but in the owners manual they say to check the relays under the hood by the master cylinder. There are 4 relays in this spot. 2 that are in line with the master cylinder and 2 against the battery. The book refers to the postitions as 41 & 42 in the fuse block. They aren't there? which of these above relay positions are 41 & 42????

 

What year and engine? In all of the cases I have seen, the 4WD shift relays are in a small relay box by themselves. There are two identical relays and nothing else in the box. The box is wrapped in electrical tape from the factory.

 

My truck is a 1999 7.3L diesel. I found the box you refered to and will replace those relays. If this doesn't solve the problem, where to next? Everyone keeps talking about relays in the dash behind the radio, are there any there?

Thanks for your help!!

Wyatt

 

chamber, I tried changing the relays. nothing. the next step would be to have the GEM checked according to some posts on another diesel truck site. I really do not want to spend $400-500 on the GEM, any ideas where to find one, Ford part number is F81Z-14B205DE. The dealer says these are year specific and will not interchange. Have you got about what else it could be??? I'm getting very flustered with the problem.

Thanks for any and all ideas

Wyatt

 

Have you checked for power at the shift motor? Unplug the two wire plug from the shift motor on the transfer case and put a test light between the two wires. Have someone turn the shift **** (with the key in Run). The test light should light a number of times as the relay's try to activate it.

If the test light lights, then the problem is most likely the shift motor itself.

 

I also am having issues with my 1999 f350 4x4. The four wheel drive just decided to stop working the morning of our blizzard. the light does not come on the dash. I changed the shift motor on the transfer case but still does not work. I checked for power at the fuses under the dash and also under the hood. All fuses test fine. I have no power at the dash board switch and no power at the transfer case. I do not have a shop manual so I do not know where to go next. Someone mentioned two moduals under the hood next to the fuse box. What are these for and should I be changing them.

 

Read what I've written above. Find the shift motor relays, they are in a relay box, under the hood, drivers side. Two identical relays in a box by themselves, nothing else in it. Swap the positions of the relays and see if this doesn't allow it to shift into 4WD. If the works, replace both of those relays. They are pretty cheap directly from the dealer.

If this doesn't work, do the test I described above with the 2 wire connection to the shift motor and the test light.

 

I've been reading about the 4x4 issues. I'm having issues as well, but my light comes on in the dash. Is this just a fuse, and if so, which one should I look at? I tried looking at the relays under the hood and they looked fine. Suggestions??? Supposed to snow again tonight....it stopped working on last snow storm! It's a 2000 F250 w/7.3ltr engine

 

I too am having problems. No light, new shift motor, switched relays, checked fuses, switch on dash checks out ok with meter (correct mA's). The transfer case is currently in 4X4, no light, no codes, won't switch to 2H or 4L. Should I have the GEM checked? Would a used GEM have to be from the same model with the same options?

 

Dave, try checking the vacuum hoses. That's what I found was wrong with mine. Although my light did come on in the dash. Just a suggestion.

Kevin

 

If you checked everything else I would try the Gem. Did you check the 4x4 module? It sits on the inside of the fender next to the battery. I would probly check the module first because its much cheaper then a GEM module. Also the Gem modules are specific to what truck they go in. You would need to pull the Gem off and get the number off it.