Hi I own a 2003 Ford F150 5.4 triton auto four wheel drive with the electronic switch. The problem is when I put it into 4high or 4low, it almost always goes in but it doesn’t go back into 2wd. I have to do some special procedure that keep forgetting to get it back to 2wd.
I took it to a mechanic who spent a few hours diagnosing the problem and concluded “the problem is electrical and it’s a relay in the dashboard that’s difficult to get to” he took off the oval cover and pointed at the 3 relays right under the cover and said “the relay is under these 3 relays” and yeah it seems very hard to get to. I was wondering, is he correct that the transfer case relay is in the dash somewhere? Also he ruled out the under the hood fuses, and easy to access and test relays (the ones under the hood and the ones under the steering column) He also tested the transfer case motor and said there’s nothing wrong with it. 4WD wise I have already changed the 4WD actuator and fixed a vacuum leak from a hose that goes from the front diff to somewhere near the battery. Any ideas or insight or tests I should do helps, thanks

 

The engine computer has nothing to do with 4wd.
A GEM module located on the back side of the dash fuse panel controls all the functions.
Yes, the relay pack is in the center of the dash.
The GEM controls the relays that apply power to the case motor due to high currents involved.
The relays are fed separate fused power to operate the case motor.
The case motor is a DC motor so will run in reverse if the voltage source is reversed from one of the relay's . This how it takes the motor out of 4WD hi and low.
The dash position lights are controlled to light by the GEM when the firewall solenoids send a ground back to the GEM per function.
The dash relay module is all but un-obtainable unless you get one from a yard truck.
Good luck.

 

Thanks Bluegrass. This truck has been bothering me a lot, not sure what I wanna do with it anymore really. Do you think the trucks with the stick shift 4WD have less problems vs the electronic switch 4WD? These 10th gens are old trucks so I probably shouldn’t complain as most old trucks with a bunch of miles will end up having similar issues I’m guessing.

 

I'm a bit biased to fixing the system because I know all about it.
My 02 has 321+ k miles on and 4wd still works perfect.
The only service it needed was a firewall Solenoid. These solenoids have a filter under the small round cap that dries up and turns to bits falling down into the plunger area locking it up. Then the front Actuator does not get any vacuum to operate.
If the truck still has lots of miles left and you want to delay getting another, it's repair time.
Vehicles now are over priced due to the countries problems and lack of parts to build new ones.
Many dealer lots are not full like they used to be.
Buy a newer truck after 2015 and be prepared to not repair it yourself like the older ones because the complexity is several times that of older ones.
Almost nothing is the same any longer.
Lights are even all controlled via Module programming.
Electric steering, electric rear brake operation and the list goes on.
Good luck.

 

You may want to watch this video, parts 1 and 2, to learn more about the 4wd and where the parts are located inside the dash.

 

Awesome, thanks for the link! That video seems very promising, I’m seriously considering taking out the relay module in-between the cluster and radio and having someone solder the connections new. I’d do it myself but knowing from previous experience I have a very shaky hand and I’ll surely mess something up lol. I’m guessing a computer repair shop will be able to solder

 

thanks for the video link I had a local electronic repair shop resolder all of the joints on the module and so far so good, it goes in and out of 4 high and low smoothly and swiftly. 😁 they said 3 of the joints had cracks but they decided to resolder every joint just so they all can be new

I don’t have a before photo but here’s the after, the joints aren’t cracked anymore 😀

 

I also changed these two solenoids, so far so good no problems, although these fail too I think the actual problem was the transfer case relay but changed those two out anyways just to have them new… they don’t cost an arm and a leg and take minutes to replace

 

Sorry I was gonna upload something else but changed my mind, idk how to delete posts so here is a pic of a test light 💡 lol. It has the wire taped on top so it can test the 4WD vacuum solenoids