Please i hope someone has had the same problem and knows how to fix it. My four wheel drive will not work with shift on the fly I have changed everything the switch on the dash the vac switch under the hood the relay switches the electric motor on the trasfercase. i can manually engage the hubs and they lock in i have even taken the electric motor off the transfer case tested it and it works fine. I took a wrench manually turned the shift *** on the trasfercase and the four wheel drive will work but electriclly it will not work. please help

 

It was after all the relay switches that it seems no one knows about under the hood. they are located on the drivers side in between the master cylinder and the fender there are two black boxes. the one closer two the master cylinder has two relay switches in there one makes the motor electric motor that switches the transfer case from two wheel drive to four high and then to four low. the other makes it go back from four low to four high then back to two wheel drive. So if someone has a problem with there transfer case not changing this is the problem it has nothing to do with the hubs thou. my vac to the hubs don't work but i can manually engage the hubs this is all i care about screw the electric shift ****. give me back the good old days of manual everything. everyone has got to lazy to get out and lock it in. If you can't get out to lock it in you don't need a 4X4.

 

OH BY THE WAY THE FORD DEALER DID NOT EVEN KNOW THERE WAS RELAY'S THAT WORKED THE FOUR WHEEL DRIVE SHIFT ON THE FLY. BUT THIS SHADE TREE MECHANIC FOUND THEM.

 

Actually a lot of people know about them if you would do a search on it in here.

 

LOL i have been everywhere for two weeks since i bought this truck and i have not found it. I knew there had to be a relay and went to ford and asked the part guy for a relay for the shift on the fly and he said there was none. but i know enough to know there had to be one some where. I found them by messing with my friends F250 while he was putting in and out of four wheel drive listening for a click while the engine was off. i herd it under the hood and found them on his truck. But i am amazed that they are not listed in the manual under relays. i am more amazed that the parts guy at ford did not find them in there parts. But thanks anyway. I am glad to have four wheel working now i can put my boat in on the beach again.

 

You can switch them around in the future to detect a bad one.

 

Well I am having some what of the same problem. 4X4 won't engage. The 4x4 light comes on, on the dash, tried the relays can still hear the shift motor engaging. Any other ideas?
becides tearing into the transfer case

 

Are you sure it's not your vacuum? Do a search.

 

yes, i believe it to be the vacuum. Changed out the vacuum switch that is on the fender. still didn't solve the problem.
The passenger side line has vacuum at the hub but the drivers does not

 

They both need vacuum and you should take the hubs apart and clean/grease them & check the seals before you do any more.

 

i still don't have vacuum to the drivers side traced the line couldn't find anything. Even without the vacuum the hub shoudl still engage in the lock position correct ? Took it to a shop and they said the hubs were bad but i don't think they checked for anything vacuum related

 

It's already engages in the lock position but it would still go through the motions. There should be vac lines comining out of the top of both knuckles near the ABS lines if you have that.

 

yeah i have checked the vac lines the drivers side has nothing still trying to figure out the leak very hard to find.
the hubs should engage if the hub are locked in, and the 4x4 turned on correct ?
sorry i am just wondering if i don't have a bad hub and a vacuum leak. but i hope not

 

You don't need to lock the hubs if you have vacuum powered (ESOF) system.

 

Just wondering if I could still should be able to get use of the 4x4.