My 4x4 doesn't work when I turn the dial in my cab. No light comes on in the instrument cluster for either 4x4 or low range. Fuses are fine- checked those. I replaced the switch, however I haven't checked to see if it was getting power- how do I check this with a multimeter or test light to see if it's getting power? I checked the solenoid harnesses today with a test light connected to battery terminals, the 2wd was getting power/ground, and the ground on the 4wd was good- but when I switched to 4wd, I got nothing. I checked the solenoids, neither one showed any resistance on the ohm meter. They are the older style with no plastic "roof" over them, so I am assuming they are fuq'd and I'm just going to replace those. Is it too early to say it's GEM, or is it possible that there is a bad relay between the GEM and the solenoids. Before I test vaccum, I need to get this part going- then look at the transfer case shifter. Snow will be flying soon, so I'm kinda getting anxious to get this taken care of. Thoughts?

 

Learn how to use your meter and be methodical in your testing. Make a list of what is supposed to be, then measure and see if it is.

You can waste a lot of money and make things worse if you don't make a good plan and execute it. With some basic meter knowledge and some time spent making a plan you'll be surprised at how much you'll learn once you start testing. Good luck.

https://www.youtube.com/results?sear...+to+multimeter

 

I double checked on youtube to make sure I was using the right settings/plugs on my multimeter- and I was. I even made a test harness for the leads with some wire and a couple harness pins In my electrical kit- checked to make sure they were touching both pins inside the solenoid- nothing on either one for resistance. Should have shown around 70 ohms per a youtube video that I watched. I don't have an OBDII reader, so I haven't pulled any codes off that yet, and I doubt they 'd be able to do that down at Autozone, haha. Knowing what I've seen today- just looking to see if I'm on the right path- going to have to back track to the GEM, but how do you check to see if the GEM is the problem, or if it's just a relay- huge difference in price to replace, lol.

 

I think that you need a wiring diagram to see when each device should be getting power.

What year and model?

https://www.f150forum.com/profile.php?do=editsignature

 

Do you have esof?

When you turn your vehicle on, if you have electronic shift on the fly, a self test is done. If it fails the self test the system is disabled and all your testing is not going to help.

No lights, no relay clicking, nothing.its dead.

The shift motor is responsible a large portion of the time, it's a common failure.

There is no feedback from vacuum solenoids or the front end disconnect, the computer has no idea if they work or not it only knows if electrical circuit conductiviity for the vacuum solenoids is intact.

 

I do have esof, I've replaced the dial on the dash with a new one. I also got a new pair of solenoids. Going to get a new transfer case shift motor next and get that replaced hopefully this weekend. So if I am understanding the other posts correctly, the shift motor more/less "completes" the circle and tells the computer that everything is functioning? Are the solenoids and axle actuator a separate system, or do they all work in unison to make the esof fire off? I also bougth the sensor for the t-case that runs the dash lights. Looks like I'm going to have an afternoon under the truck in my near future. It would have been easier for Ford to just leave the 4x4 as a manual shift, lol.

 

The shift motor is a known failure point it's not uncommon. When it does the self test if it does not know the position of the transfer case it disables everything. It's highly unlikely your switch or anything like that had anything to do with it. In fact there is a code in the PCM most likely that can be read. That's how I found out mine didn't work once, my vehicle was at the dealer for something else, and as a matter of procedure they read the codes... Told me what needed to be done....

 

Should I stay away from the Dorman or other "aftermarket" shift motors and go with a Motorcraft one, or would the aftermarket one work just fine. Looking to extend the life of this truck BTW. Truck has 215K miles on it, and with used pickup prices the way they are......fixing this one up is more fiscally responsible, haha.

 

Aftermarket is fine just make sure you get the right one. There's multiple that look exactly the same
.
If you get it from Amazon you might be able to send it back if that wasn't it.

 

Since I work at a repair shop, I've got an "in" on getting a discount on parts at places like NAPA, which pretty much sells DORMAN shift motors. Between those guys and RockAuto.com, and I also get a discount from our local Ford dealership on parts through work (they are a Ford/Dodge dealer), but it's not as nice as what I get with NAPA- plus NAPA delivers to us, lol. I'm sorta old school- would rather get my parts from a dedicated parts place than take my chances on Amazon. I'm a parts guy myself, so I'm just funny about that.