Adding 4H Switch (18-21)

[HILLY]

I came across this video where the guy added 4H button functionality that's not readily available in the 18-21 trucks without having to scroll through the drive modes (Mud/Rut for one). He grabbed the 22-24 drive mode switch version that has it and was surprisingly plug & play.



Just FYI for those interested. Around $55 at the time of this post.

With 4L - NL1Z14B596BA
Without 4L - NL1Z14B596CA

Add 4wd Hi Range to your 18-21 Ford Expedition!

Easily add 4WD HI to your 18-21 expedition!part i used: 22-24 4wd switch with 4LO is NL1Z-14B596-BApart without 4LO for those with 1 speed transfer case is N...

youtu.be

Now, for those of us who have HD tow or a similar setup where I won't lose the rear locker setup doing this upgrade alone, I'm curious if the 22-24 gear selector switch (NL1Z7P155C) can be upgraded in conjunction with this to complete the upgrade.

 

[Trainmaster]

It's hard to imagine that both these options would share the same transfer case.

 

[HILLY]

I'm surprised his switch has 4L without the rear locker. I had originally thought that the 4L option was only available in conjunction with the HD tow or FX4 package which would have also included the rear locker. That said, he also has the column shifter in his truck, so I wonder if he also has a an SSV which would have had 4L without locker?

The center diff is computer controlled to vary slip all they way up to lockup. So I would imagine that in theory whether 2-speed or not, a 4H signal would lock up the center diff which can still be advantageous whether the 4L button is just a dummy in this case if you don't have the xfer case.

In the end, I guess mud/rut mode should still give the same result. Some people may just like the ability to simply hit the switch regardless of drive mode (Normal, Sport, etc.).

 

[Rob6805]

The switch shown in the video (2H/4A/4L) is exactly what we have on our 2021. It has HD tow but no ELSD.
So... I would LOVE it if it's that easy to get 4H by pressing a button (like 2022+) without having to go into the drive modes.
For ~$50 I may try it and see what happens.

 

[HILLY]

It's an expensive endeavor, but I'm tempted to try the transmission selector with the eLSD feature. If I were to come across a reasonable junkyard find, I'd be all over it. On the 2WD models that lack the selector switch found on the 4WD models, the mode selection is indicated by the blank plate located between the +/- buttons. The switches must send a unique CAN signal to the control unit. I still find it too easy that he was able to swap the switch without any programming or changing any FORScan settings.

 

[Trainmaster]

.

 

[Trainmaster]

It may be a good idea to root around the F150 forums. There are more truck owners who are skilled mechanics in that community and lots more messing around with the f150s than with the Expeditions.

I truly doubt adding a switch would replace drivetrain hardware changes.

I've learned much from them. Their trucks are very similar to ours.

 

[pnwjetsled]

I personally would love to lose 4A in favor of having a real transfer case. We use 4A all the time, not on pavement. Backing down a hill, especially with a trailer sucks when it’s dragging the front tires when it should be in 4x4 helping.

 

[Rob6805]

Did a little research..
The drive mode/4WD button assembly is the ATCM (All Terrain Control Module). It is indeed on the vehicles CAN bus (HS can). It sends signals to the TCCM (transfer case control module). I'm working on getting the database (DBC file) that will show me what the individual signals are for each button press.
I had thought, and it still might be the case, that the FX4 modles from 18-21 had the 4H option. Still trying to confirm. If this is true, or even not, simply replacing the ATCM with a unit that has 4H may indeed send the proper signal to the TCCM for this mode. The key would be whether the TCCM would recognize that signal and swith to 4H mode.
Worst case if you tried it and the TCCM rejected the signal nothing would happen.
Also, so we are all clear. There are only two different transfer cases. A single speed and a two speed (4L option).
I'm 75% on going for it and spending the ~$50 to try it.

 

[HILLY]

I just found an FX4 for sale, and this was the setup. No different than what I have with my HD Tow (2-speed transfer) with eLSD.

At this point, I don't see why anything won't work as long as the harness matches up and the signals get to the same endpoint at the control module.

 

[Rob6805]

I just found an FX4 for sale, and this was the setup. No different than what I have with my HD Tow (2-speed transfer) with eLSD.

At this point, I don't see why anything won't work as long as the harness matches up and the signals get to the same endpoint at the control module.

View attachment 86476

Good find. For some reason I thought I've seen folks saying their 18-21 FX4 had 4H button but apparently not.

Agree that it's still worth a try.

 

[Rob6805]

I asked the you tube guy if 4H worked at any speed and he confirmed that it did. He also mentioned that Mud/Ruts mode (4H using drive mode setting) also worked at speed. Not sure why I've seen some posts that state Mud/Ruts turns off at certain MPH. I've never tried it with mine but good to know it does not.
Going to pull the trigger and order the new switch.

Add 4wd Hi Range to your 18-21 Ford Expedition!

Easily add 4WD HI to your 18-21 expedition!part i used: 22-24 4wd switch with 4LO is NL1Z-14B596-BApart without 4LO for those with 1 speed transfer case is N...

youtu.be

 

[pnwjetsled]

Good find. For some reason I thought I've seen folks saying their 18-21 FX4 had 4H button but apparently not.

Agree that it's still worth a try.

That was my understanding too after we got our max tow xlt. I was kind of bummed. Makes it better knowing they didn’t get a true 4H either. I have always wondered why all electronic wise would be needed to swap in a f150 two speed Tcase.

 

[Rob6805]

Received the part today.
Will install tomorrow and report back.

 

[Rob6805]

Got it installed and 100% works.
Super easy to pop out the console lid too. No screws. I ended up removing it entirely because I had to clean under it. (wife is a smoker).
And now there is a 4H lit up when it's in that mode. All drive modes work as expected too. I'm sure this is identical to the 22+ now.

 

[EricRomanov]

I have also installed the 4H Switch in my 2018 Max, Limited with HD trailer tow. Works great! But, also tried installing the upper shift selector switch that has the diff locker switch. Running into the dreaded "not being recognized by the TCCM issue". Does anyone know a way around this? Forescan possibly? Thank you Sincerely to all who posted here. Great info!!

 

[Rob6805]

I have also installed the 4H Switch in my 2018 Max, Limited with HD trailer tow. Works great! But, also tried installing the upper shift selector switch that has the diff locker switch. Running into the dreaded "not being recognized by the TCCM issue". Does anyone know a way around this? Forescan possibly? Thank you Sincerely to all who posted here. Great info!!

Where are you seeing the error message?
Just a suspicion.. but now the CAN message for the diff lock is being sent to the TCCM by a different module (shift selector instead of the ATCM) and it's being rejected. TX (transmit) CAN messages are addressed and now the TCCM doesn't have the logic to process it.
Doubtful Forscan would help with this. It would require a SW change. Possibly flashing the TCCM with 22+ SW file might do it (if it's possible).

 

[HILLY]

Where are you seeing the error message?
Just a suspicion.. but now the CAN message for the diff lock is being sent to the TCCM by a different module (shift selector instead of the ATCM) and it's being rejected. TX (transmit) CAN messages are addressed and now the TCCM doesn't have the logic to process it.
Doubtful Forscan would help with this. It would require a SW change. Possibly flashing the TCCM with 22+ SW file might do it (if it's possible).

I'm curious - and I haven't physically looked at the harnesses yet - if it's possible to repin the plugs? Move the signal wire for the locker from the drive mode switch to the gear selector? I'm not sure if my logic is sound, but it seems the wire could been moved to a different harness wye.

 

[Rob6805]

I'm curious - and I haven't physically looked at the harnesses yet - if it's possible to repin the plugs? Move the signal wire for the locker from the drive mode switch to the gear selector? I'm not sure if my logic is sound, but it seems the wire could been moved to a different harness wye.

This would not be possible. All CAN messages into (RX) and out of (TX) modules are across the twisted pair High(+) and Low(-) wires. There are no dedicated wires for a certain signal. Each module, like the ATCM, has an address on the network. The SW in the module controls and manages the signals that are sent and received. So for example, the ELSD button that is on the ATCM, pressing it sends the proper signal out on the Bus to the module which is the mapped receiver for the signal.
It's pretty complicated.. And frankly I was really surprised that just swapping the ATCM with the 4h button actual got 4h to work. The logic had to have already been implemented and for whatever decision Ford decided to go with no 4H button..