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Discussion Starter · #1 ·
2008 6.4 F-250, When I start the truck the 4hi and 4low lights come on and cycle but thats all. When the selector is moved there is nothing that happens. I have ohm'd the switch and all is well, I have checked all the related fuses and all are good, I have verified voltage and again all seems to be good. this is really stumping me as I just bought this truck in March and shame on me for not checking this but I somehow let it slip my checks before purchasing so shame on me.. But I hoped that before I take it somewhere that maybe someone here had some input...
 

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Just went through this with a client, yellow wire at upper tcase encoder motor was corroded and was broken.

Check the wires, if not your motor is shot. It grounds the circuit internally to make the light go on.


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Discussion Starter · #3 ·
Just an update, I have since replaced the Trangercase motor, vacuum actuator, all vacuum lines, and the switch on the dash. Because the new motor came in 4Hi I had to manually put the tcase in 4Hi so now, it’s stuck in 4Hi… nothing seems to work.. I am in the same pace I was when I started ..
 

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You should of tested all those parts not just changed them.
Take the motor out the one on the vertical face of the tcase, 6 wire connector, get under while someone turns the button on the dash, if the motor doesn’t move you are not getting a signal, then try and move the tcase shifter manually you can do it with your fingers I believe all the way forward is 2wd and all the way back is 4 low, if you can move it freely good. If not it’s mechanical. Have you checked the wires like pulling back the sheathing and looking for cuts and broken wires?


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You would need to look at a pinout, for that motor and you can use a battery and jumper cables to feed power so long as its not a 5v signal. But you can use a jumper wire to get it at least into 2wd then manually put the tcase in 2wd so you can drive it, while you figure it out.

Like I said I had the same issue and it was a broken yellow wire. On that 6 wire connector.


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I have also swapped relays and checked all fuses again to no avail.. I am starting to wonder if it may be the 4x4 module to which I don’t know how to test… I am not getting any power to the transfer case motor..
Okay so you check for power at the tcase motor found no power yet still changed it..
you never said you checked for power. Not too sure why you changed all that needless stuff.

Okay. Fusebox in passenger footwell probably is the culprit. Windshields have been known to leak on the seam at the A pillar on these trucks and it will leak onto the SJB which houses the 4x4 module.

Check that for any corrosion. I’d start doing continuity tests but also if its a multistrand wire and has one wire left out of 6 it’ll have continuity but too much resistance for powering up the motor, voltage drop test could be needed.

Go to the passenger footwell inspect that fusebox. You need a diagram and a pinout for tests. I’m on Vacay for 2 months and I’m lucky I get time to check the forums lol so don’t ask me for a wiring diagram atm.


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Discussion Starter · #9 ·
Update!!

Under the fuse box under the hood I found multiple wires that had rubbed through, one of which went to the the relay and the other two went to the Transfer case motor. I repaired all the wires and I'm back in action. I found it extremely hard to find much information on the 2008-2010 F-250's.. So I hope this thread helps someone and they don't have the same headaches I have had this week..

Best Regards,
 
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