My F350 won't shift into 4wd, and after changing out the transfer shift motor with no luck, I took it to the shop.

They found that the owner before me did some "creative wiring" to the 4wd system, and that he had a chip hooked up.

I found that the previous owner had replaced the auto-locking hubs with warn manual hubs, and disconnected the vacuum to the hubs.

He also added some wiring to the dash 4wd switch, but we can't figure out what the extra wires to the dash 4wd switch were for.

The shop figured the chip, along with the wiring changes probably blew the GEM Module.

I knew there was a chip, because a hypertech came with the truck, and I used it once to put the truck back to stock, so I may have blown the GEM doing that!

I am going to try disconnecting the batteries for a few hours to see if the GEM cleans itself out.

Anyone else ever have this problem, could it be that the GEM just needs to be reprogrammed?

Any other suggestions?

 

Don't know about the GEM, but the switch was probably to have 2WD low. You should see the wires I have run through mine for different things I've added. I'm glad you've got the fix narrowed down.
Joe

 

Thanks for the response Joe.

There are two additional wires tapping into two of the four wires in the dash switch, but I personally can't figure how they could change the 2wd system.

How can adding extra wires to a Dash switch, make it 2 low, when the switch only indents to 2wd, 4 hi, and 4 low?

 

I can't really answer the question. I did mine electrically out under the hood. When you start thinking about, if he changed out the hubs it wouldn't make much sense to make a 2WD low switch.
Joe

 

Is the guy you got it from still around? That's the best answer for the puzzle.

 

Maybe the extra wires are for a locker (like an air locker or something and didnt want an extra swith on the dash).You can look at the diffs and see if there is a wire or air hose going to it. Thats what a friend of mine did. Just a thought

 

I am very interested in putting in a 2wd low switch in my 2002 7.3L auto. Can you give me some details on how you did this.
Cheers Rod.

 

the best way to do this is to upfit warn selectable hubs on your truck and when ever you want 2Low just shift into 4Low and do not lock the hubs that IMO would be the best solution so if down the road you want the convinience of shift on the fly you can put your stock hubs back on

 

(Tongue planted firmly in cheek ...) Just pull that transfer case lever to 4WD Low without locking your front hubs...presto 2WD Low! If you have ESOF transfer case, I have no idea.

 

Or if you have auto lock hubs, you can wire a switch into the hub lock solenoid. This way you can disable it, shift into 4Lo and the front hubs wont lock in.

 

imo the best way to get 2Low would be what i described in my last post you could jerryrig it but the other way is better

 

If you have ESOF 4x4 and want to use 2x4 low, just take this connection off and you will have 2wd low. Unplug this plug.

 

why would you say adding a switch inline is jerryrigging? it should have been a factory option!

it sounds like a damn fine idea to me, and is a whole lot cheaper than manual hubs!

and if you go to sell the truck is easily reversible and no extra parts to store or sell...