I have a 2003 Ford F250 that has the switch on the dash to shift from 2wd to 4wd. The transfer case will shift from 2 to 4 to 4 low, but not back the other way. I can jump the motor on the transfer case to get it back out, so the motor is good. There must be a relay somewhere that switches the polarity to the motor, but I don't have a schematic. I checked all the fuses and tried swapping the relays in the fuse box to try to get it to work, but no luck. Is there another relay under the hood? This is not an issue of backing up and going to neutral. When trying to shift out of 4 low the transmission is in neutral.
Does anyone have a schematic?

 

The low/high~high/low relays are inaux relay box 3.. Drivers side firewall area.. #3 is inline with the firewall, and 2 & 4 are more forward.. Try swapping the relays and see if the fault moves with the swap.. Both relays share the same power distribution/fusewith the 4x4 control module in control of the coil side ground to close the contacts..

 

Thanks, I tried that with no success. We also removed the relays and tested them and they are fine. All the fuses are good and the motor and plug are good. I'm convinced it's a wiring problem, but without a schematic it's hard to trace the wires.

 

for this kind of concern you really need a scan tool to watch the 4x4 parameters to see if the motor plates(in the shift motor and tranfer case)are shifting correctly i have replaced SOF transfer case motors for this concern, the switching and reversing occurs in the transfer case motor plates and motor assembly.

 

man i have built a manual unit for the diesel transfercase that has the switch 4wd it keeps the housing that the motor mounts to and it links to a manual shift box it still shows what you are in on the dash i sell them for 200.00 plus shipping this comes with a simple how to mini dvd that actually shows how easy it is to install it is a patent design

 

if you would like one contact david bolding at 704-650-3957