Hello group! Have an issue I'm hoping can be solved through the community. Thanks in advance for any help.

Truck Info- 2003 Ford Super Duty, automatic trans, 5.4
Daily driver, 260,000 miles. original engine and driveline. Well maintained as far as repairing and replacing broken parts and trying to stay ahead of problems! From Buffalo, NY. Does a lot of plowing in winter and towing in summer. Eliminated vacuum hubs with Warren Gold manual hubs.

Current issue- The other night while out plowing, my truck was stuck in 4x4 high. No problem figured fuse or solenoid maybe...finished plowing and parked at shop. Next day still stuck in 4wd High so we begin diagnosis. Tested solenoids both by swapping with others and changing positions. All checked out good. Fuses checked out good. No corrosion or broken wiring below solenoid boxes, or on solenoid contacts period. Unplugged wiring harness at 4wd shift motor and did not appear to be getting power at plug. Kinda baffled at time and out of time went to bed. Woke up next morning (had left the 4wd selector switch in the 2wd position) and truck was now in 2wd. Great thought maybe something was just frozen and had thawed...nope now I couldn't engage 4wd high. Now stuck in 2wd and snow coming! Get it to shop, remove shift motor off of transfer case test while off of truck but obviously still plugged in and BAM works great--light on dash lights up, you can hear the shift motor throughout the switch from 2wd to 4wd high and back again multiple times. Bolt back on transfer case, and BAM nothing now...WTF. Even more stressed and baffled remove the shift motor off of a back up transfer case we have on shelf and try that one...same thing works off of truck, once bolted to transfer case it wont work...HELP ME PLEASE. (as far as the switch motor from parts transfer case, i'm not sure of its original state as it was on the transfer case when I purchased it with a transmission, but it does work off of truck (but obviously plugged in) DO THESE SHIFT MOTORS GET WEAK per say or is it they work or don't?! As for now, we have engaged 4wd high with a wrench and are using our manual hubs as an in and out switch to keep the truck plowing. If it helps with thought process, it did not take any special effort to engage or disengage 4wd with the wrench. Any thoughts or advice much appreciated!

 

Wow sounds weird...I dont think grounding the motor should change anything but!
I would look at the wires or connector...Maybe when moving to a certain position the connection will be lost. Dont bolt it up just touch metal to metal and see if it stops..
Hook up the connector and hold in place wiggle around see if you can get it not to work.

Do you hear it trying to work? or nothing at all when bolted up.

 

Put 3k of sand in the back. You wont need 4wd. LOL

 

There is no activity with motor once bolted on, you cant hear it try to activate or anything. Not sure if you can feel it maybe trying..will have to have an assistant for that one. Weight works but makes for rough ride once frozen lol...

 

Rough ride? I have a sander full rides great.

 

How are your grounds? I had a somewhat similar problem recently and it turned out to be the 4 wheel drive module up above the glove box. It had gotten water into it and had shorted out. Intermittent problems like you are having have driven me nuts before only to discover later that it was a problem with grounds in particular (I live down on the Gulf Coast and our humidity does evil things to wiring like the salt and snow would do to yours.) Did you unplug the wire on the bottom Right side of transmission that has the two connectors or the one on the Drivers side that has the 6 wires? I do not think that you would be unlucky enough to have TWO shift motors be bad at the same time in the exact same way. When you are having the problem do your 4 wheel drive lights in the dash work? When my 4 wheel drive module was fried these did NOT work as they get the signal from the module from what I can see on the wiring diagram. I am no expert but I do love wiring troubleshooting and I would check grounds first and then check resistance of my wiring from shift motor back to 4 wheel drive module. It is possible that you have a broken or subprime wire connector in plug also that when you change position that it causes an open circuit. Checking resistance should find such a problem. Mike1 attached a wiring diagram that was very helpful to my thread. If you need me to attach just the 4 wheel drive segment with some tips that I learned I would be happy to do so.

 

 

I had a similar issue with my 02, except it locked in 4low. What ended up being the issue was the harness to the shift motor had worn and one of the wires was grounding or shorting. With all the salt we get in the north east it might be your issue.

 

As others have noted if your wiring harness or plug has an insult to it the problem may just present itself upon manipulation or a change of position of the wire or plug. All of this is easily diagnosed by testing the resistance. Thinking about it more I would probably check the resistance on wire and plug from the shift motor working back towards the fromt of truck. To answer your question about grounds I have seen grounds do the strangest things imaginable. Actually ground problems are much more ghostly in my experience than power issues. Plus ground points are always neglected and love to get corroded and cause many headaches. And they are such a simple fix when they are the problem that they have become my typically first things to check.

 

Thanks for the input. I’m going to start looking for a bad wire today. I will update post as progress is made or not! Thanks again

 

Ok so here is where I'm at: Hopefully gives some more info that can result in a little more advice on which direction to move in. Thanks again in advance.

1st- removed relays and did a continuity test to verify everything ok...checks out good
2nd- using test light tested all listed fuses regarding anything for 4x4 - all tested out good. for good measure tested remainder of fuses in panel and found one -trailer-tow lamps that was bad!
3rd- tested actual relay "sockets" had 12v at 86 and 87
4th- plugged one of the two shift motors in...did NOT bolt on...engaged switch and motor worked as should. Bolted to truck and nothing. DAMNIT
5th- plugged in 2nd shift motor, did not bolt on (that worked prior, see original post) nothing - OH MY
6th- begin the fuse check again..all good.
7th- relay check...all good sockets and relays
8th- begin testing for power/voltage at harness plugs - tested with power (ignition) in on and off position and with 4 wheel drive switch in both 2 and 4 wheel drive- results were identical regardless
RESULTS- orange wire with white stripe -
brown wire with yellow stripe-
brown wire with white stripe-
tan? wire-
All these wires had 13.2 volts +/-. This was done with a volt meter. However on a side note we also used a test light and for some reason test light did not light up even when registering 12v ?! WEIRD or no??? yes test light is good - confirmed both using to test for grounds as well as confirm power with fuses, relays etc. !!

Black wire with pink stripe- ground
orange wire ???? no voltage and not a ground????
9th- we also disconnected the positive AND negative battery terminals and zip tied them together. This was done to hopefully reset the computer in the thought process of maybe we somehow put the 4wd system into a safe mode or something?
10th we used jumper wires to hot jump the motor. It functioned but sounded very strained, so we dismantled the shift motor to discover what if anything we might see that was internally obvious as a weakness or cause to function when not mounted but fail once bolted on and make it sound so strained. What we discovered was that the gear that was attached to the input area for shaft (hope this bad description gets you to area being implied! lol) has a brass ring around the circular part of gear. This particular gear could not be moved or rotated by hand at all (middle gear was removed). We popped this all apart, cleaned up extremely well and reassembled. Gear now rotates very freely. Re assembled unit and tested again with direct hot lead...sounds much nicer and doesn't sound strained at all. Works both ways (leads switched). So now hoping that this would solve problem, but still no luck...what do we do from here?!

Inspected wiring and harness...everything looks really good with visual inspection. While truck is definitely from BUFFALO, NY it is actually very clean on the wiring and under hood side of things!

 

must use test light at times as meter can give a false reading. Don't know why you were testing all the fuses relays etc when you said the motor worked unbolted. if the motor works in your hand will it work with a test lead metal case to transfer case or just touch transfer case with it? does it try to work bolted up. and if not at what point does it stop working?

 

All that crap goes through the gem module . I don't have a drawing for an 03..
I have drawings for 99 and 05 yrs. Get a new motor to try would be my recommendation.
You need a drawing to find out where grounds are.

 

 

Orange and yellow wires will turn the motor one way or another if you switch ground and 12v on them. if you do this and the motor wont turn the transfer case then the motor is bad most likely. This drawing is for a 99. Be careful don't short out anything. You can also ground out with a test light the relays under hood.