Hey guys, got a call back from my mechanic, after much testing he determined the problem is within the GEM itself. THere was zero fault codes for the shift motor or the dash switch. He believes it is internally corrupted and basically thinking that the dash switch is being moved and it is seeing a request to shift. So part# F85Z-14B205-NA is going to be ordered, best he can do for me is $250

I was hoping this module would have worked! bout $100 cheaper!

http://cgi.ebay.com/ebaymotors/ws/eB...K%3AMEWAX%3AIT

 

lad to see that the GEMlins were found and are being dealt with.

 

I hope its the end of this fiasco!

I don't know if my tech fixed it or not, may have not noticed it and I failed to remember, but what do I do for the light in the dash switch? Is there a fuse I should check for it first? Can I even get a bulb for it?

Thanks JMC, this has been a valuable learning experience!

 

You will need to pull the bulb to see what it is. Shop manual doesn't give bulb number. Dealer will have replacement but maybe radio shack will too.

 

Hey FordGuy, Did the GEM fix the problem?

 

Hey F150bryan, YEP! I just got truck back tonite, all 4x4 operations are a GO. My mech pointed out to me the corrosion on the back of the GEM board. I overlooked it before, it is soo minimal but once you look for it, it starts jumping out at you. He charged my $240 for a new GEM. I thought that was pretty good and $100 labor so $340 for everything. It was worth it, I was pulling my hair out at the end! I'll have to get some pics up for you guys of the corrosion.

He told me probably because my truck is extremely low mileage (40K on the clock) the GEM just got condensation in it from sitting around, truck not getting drove much, lots of heat/cold cycles throughout the years and not a ton of air movement didn't help.

 

Heres the pics of the corrosion and possibly shorted out resistors/transistors on the bottom of the GEM board.




one of the worst spots the whole area has white and green spots all over it

 

Boy, am I glad that I have a manual shift and a posi-lok cable on mine.

 

Thanks JMC makes me want manual shift even more! LOL Well its working like new again, on the bright side I've got a new GEM, shift motor and relay module! LOLOLOL!!! Shouldn't have trouble ever again!

 

its funny how i have the exact module and have corrosion in 2 of the 3 spots you show in the pics, well more like funny strange than funny ha ha. I so hate ford.

 

Its funny how your very first post just happens to be a negative post about Ford in this thread. Who sent you here? Come on fess up!

 

Same thing was happening to me. Riding along and the 4X4 light comes on and you here the cluck. I seen other posts and found that it really didn't go into the detail. So I added this.
Didn't touch anything and pulled the transfer case switch motor and found the post under was pointing to 2wd (switch was in 2WD). This was weird because the relay at the front by the battery for 4X4 was on(had vacuum). There are two relays the one closest to passenger side is 4X4 and the other is 2wd. One of them is always on. So the clunk is from the front engaging the hubs, but the transfer case never switched. I pulled the motor and left it hooked up to the truck. I moved the switch to all three positions and it didn't move at all. I pulled the motor completely and put 12V on the bigger yellow and orange wires and it moved in both directions fine .

This led me down other paths because turning the switch I didn't hear the relays clicking. In other posts talk about bad PCM or switch. I ohmed the switch and found it was fine (pins 2 and 3. 3.8k 2wd 1.06k 4hi).

I seen the price for a new or used PCM. Ouch.

Because I am cheap and figured it doesn't take long to put in I changed the motor even though the old one moved, maybe the feed back switches in the motor was bad.

Wallah new transfer motor it starts working.

 

THE PCM HAS ......NO-NO-NO...……….. CONTROL OF THE 4WHEEL DRIVE FUNCTION.
The PCM is engine control and transmission normal gear shifting only.
The GEM, at the request of the dash switch, controls all the 4x4 functions.
The transfer case and 4x4 functions are totally separate.
There is no basic vacuum control except for the front axle actuator AFTER the case motor runs to first position.
A random 4wd engagement is a false operation of the GEM.
Very often it is corrosion inside the GEM on the circuit board. The GEM is located behind the dash fuse panel and can get wet from a leaking wind shield or cowl seal.
The case motor cannot operate unless the relays that are controlled by the GEM operate them thus the motor.

 

If you had bothered to read the whole thread, you would have had the answers to all your questions. GEM failure.

 

Yeah mine was doing this too thanks for the input I need that , i’ll keep you updated on anything else that occurs with this truck , The truck I have is a 4.2 L V6 single cab 4 x 4