Hey guys I have a 2003 f250 superduty with the 6.0 its a crew cab lariat 4 x 4 i live in Montana and need the 4 wheel drive to work. It is automatic on the fly. When i switch the switch on the dash no lights come on and nothing happens. I've checked the fuze and that seems to be ok. I also checked all the wires on the switch and none of them have power. please help as winter is creeping up. Thanks Eric

 

Hi Eric, Things are not that simple.
4X4 overview:
Turn switch on signals a modal into action. The GEM.
The action is to run a transfer case motor to it's first position 4H.
A circuit board on this motor signals a firewall relay to allow engine vacuum to a front axle actuator.
The actuator slides a collar inside the axle housing locking the front axles together and the dash light comes on.
Your job is to check these actions out and see where it stops then why.
Remember I said it was not simple?
Once you know what is supposed to happen then it's easier to see the trouble area.
Listen for the case motor to operate, the actuator to 'klunk' in etc.
Good luck.

 

Hey bluegrass there is no klunk from the actuator or any sound at all for that matter. Even if i manually lock in hubs nothing happens. I did make sure the hubs were locking when engaged manually. Thanks for the help.

 

That's a start.
Does the transfer case motor run when the dash switch is moved from 2H to 4H?
Any action when you set still with foot on brake, shifter in neutral and go to 4L?
You have to chase this as there is no way for us to tell you exactly what is wrong.
A windshield leak could cause the GEM to be inoperative but remote in this year truck.
Don't begin replacing parts until the trouble area is pinned down.
Good luck.

 

Hey Bluegrass i crawled underneath and actually took the actuator or electric motor off the transfer case cleaned the electrical connections plugged it back in and had my wife turn the switch to 4 high and 4 low and back to 2 high nothing happened i checked all wires there is no power at any of the wires. As far as i know there is no windshield leaks it's been in a few good rain storms and no water coming in. If I have no power at the switch and no power at the actuator it seems like its definitely an electrical issue. I also started the truck and turned on the ac and switched to 4 high and it stayed on the dash and didnt go to defrost mode so I'm thinking not a vacuum leak.

 

The only use of vacuum is at the front actuator no other location. The motor has to be running for the actuator to work.
.
If there is no case motor movement then that's the point of the failure.
The GEM operates a relay to supply power to the case motor though a fuse.
If you do not hear that relay click up then it's not being signaled from the Gem to connect power to the case motor.
Either a power issue is the cause or the GEM is faulty.
Work in these two area to define the point of failure.
Look in your owner manual pages 156 and 158 for fuse 111 that may be blown.
Good luck.

 

Hey Bluegrass ive checked all the fuzes all are good. I'm going to start with the relays since that would be the cheapest and if that doesn't work then I'm thinking it is the GEM. I will keep you posted and thank you for your help.

 

Hey bluegrass thanks again for all the help i was able to narrow it down to the module. I got a new one today and swapped it out and now my 4wheel drive is working.

 

Eric what module is it that you needed to replace ??

 

Good to hear of your success.
Good luck.