I have searched and read many threads on this subject, and believe that I have narrowed my problem down to the GEM. Before I buy one though I wanted to see if you all think I'm on the right track.

We bought the truck used several years ago. Four wheel drive worked fine at the time. Within a few weeks of our purchase we started having some problems. We were in the middle of moving out of state so we took it to a Ford dealer for our daughter to pick up when done. The dealer diagnosed the problem as the PCM and replaced it. We never thought at the time to check the four wheel drive.

We never had use for the four wheel drive until about 8 months after getting the truck back and the ESOF wouldn't work. We really didn't need the four wheel drive until here lately and now trying to get it fixed. I don't know if the dealer replacing the PCM has anything to do with our problem.

The 4X4 light on the dash does not come on when the key is turned on. The esof switch does nothing. I replaced both relays and checked the connector on the shift motor and with a test light attached and the motor running I had my wife switch to 4 wheel drive high and low and I got no power.

So I think I am left with a faulty GEM but really wanted a second opinion before buying one. Also I'd like to know if there is anything else I can check.

Its a 2001 F250 Super Duty 4 X 4 with a 5.4 engine.

 

Possible bad ESOF switch. I believe that the ESOF engages the front by vacuum, so maybe you have a leak.

 

Is there anyway to test the switch or to jump any of the connecting wires? Thanks!

 

The switch has two wires. A different resistance is placed on the wires, depending on the position of the switch. See the highlighted portion of the diagram below.

You could check the switch for continuity or short. But I don't know what the resistance values are supposed to be.

 

I took the switch apart today and all looked ok. I am getting power to the switch and to the relays. I took the GEM out today to look for corrosion or moisture and it looked ok. I may have to find someone to look at this for me.

 

I'm probably going to order the GEM tommorrow. Any other suggestions before I bite the bullet?

 

This is just an update to my problems: I order the GEM from an online store that charged 279.00 compared to the 419.00 that the Ford dealer wanted. I got it today, hooked it up and now have four wheel drive again

 

I am having a similiar problem that I discovered today... no dash light at key on or startup, no switch response, and checked all fuses. Since i believe the lights are controlled by a module or controller, i am thinking it is something to do with this. Where did you get your GEM

 

I bought mine from a place called Auto Parts Cheaper Home page. Dealership Auto Parts at Low Prices. Reasonable Shipping Charges with no Hidden fees.

There is also a coupon available for 10% off at AUTO PARTS CHEAPER coupon codes - promo code, discount & free shipping coupons for autopartscheaper

Hope it helps! It did fix my problem.

 

Dutch, I heard the dealer has to reflash or program the GEM? I have also gotten conflicting reports, is the GEM behind the fuse box or glove box?

 

...SOME GEMS have to be flashed...not all...or even most IIRC. GEM is behind fuse box.

 

GEM's were installed on the 99-01 trucks and don't need programming. 02-03 have the VSM and those need to be programmed.

 

Take a look in my gallery for photos of what mine looked like when I removed it and took it apart. Pretty obvious why it did not work.

 

I'm having the same problem. No power at the switch whats the best way to check for power/connectivity at the switch. Can anyone help me out snow will be here soon.

 

The switch lighting still works, just no 4x4 on the dash at startup, or anything else.

Gonna have to take it in, my list is growing.