2LO Module - 90% Plug and Play

whizkid

Tremor Buff
Joined
Dec 27, 2021
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Location
Owasso, Oklahoma
Current Ride
2017 Expedition Limited w/ Max Tow
While I'm sitting here waiting on my Tremor build and researching all the mods I can, I'm very interested in the 2LO setup since I have a 32' RV that I back regularly. I love the idea of 2LO making it easier to control my speed while still being able to steer as much as possible.

So. . . my question for all of you out there. If I was able to make a module that went inline between the TCCM (Transfer Case Control Module) and its wiring harness in the passenger's side footwell and made it 90% plug and play such that you'd only have to hook up +12v switched power (via upfitter passthrough or whatever switch you want) and a ground (there's one readily available in the same location on the "Customer Access" harness for the PTO & SEIC functions), would anyone be interested?

I've read all of the forum posts about how to do this mod and while it's super simple, I'm just not sure about cutting into wires on a brand new $80k+ truck! I've researched the CVH control circuit and there's not a mating connector available for the solenoid connector to put one inline at the solenoid but there is one on the TCCM and I found them readily available (at least for the 2020/2021's). The receptacle is board-mount only, whic\]='[;.h is fine as I can print a custom PCB along with a 10A relay to control the CVH solenoid control wire (pin #6) and break out the relay coil wires easily. Attached below is a rough drawing to illustrate.

I'm just curious if there was enough interest in this to pursue more than just one for my own purposes. Thanks!

2LO Module Diagram.png
 
While I'm sitting here waiting on my Tremor build and researching all the mods I can, I'm very interested in the 2LO setup since I have a 32' RV that I back regularly. I love the idea of 2LO making it easier to control my speed while still being able to steer as much as possible.

So. . . my question for all of you out there. If I was able to make a module that went inline between the TCCM (Transfer Case Control Module) and its wiring harness in the passenger's side footwell and made it 90% plug and play such that you'd only have to hook up +12v switched power (via upfitter passthrough or whatever switch you want) and a ground (there's one readily available in the same location on the "Customer Access" harness for the PTO & SEIC functions), would anyone be interested?

I've read all of the forum posts about how to do this mod and while it's super simple, I'm just not sure about cutting into wires on a brand new $80k+ truck! I've researched the CVH control circuit and there's not a mating connector available for the solenoid connector to put one inline at the solenoid but there is one on the TCCM and I found them readily available (at least for the 2020/2021's). The receptacle is board-mount only, whic\]='[;.h is fine as I can print a custom PCB along with a 10A relay to control the CVH solenoid control wire (pin #6) and break out the relay coil wires easily. Attached below is a rough drawing to illustrate.

I'm just curious if there was enough interest in this to pursue more than just one for my own purposes. Thanks!

View attachment 42694
For me I guess it would come down to cost and ease of installation. I'm not good with technical stuff but I can run wires. As long as the rest of the instructions were very clear, I'd be interested. I hope you get a good response. Good luck.
Don
 
For me I guess it would come down to cost and ease of installation. I'm not good with technical stuff but I can run wires. As long as the rest of the instructions were very clear, I'd be interested. I hope you get a good response. Good luck.
Don
Thanks Don! That's enough to get me to proceed. I'll order a few connectors and work on the board and see where it goes. Might take a month or two, but I'll ping you when I have something and you can be a beta tester for me.
 
Any idea on what it "could" cost? I'd be interested if it wasn't rediculous.
 
Any idea on what it "could" cost? I'd be interested if it wasn't rediculous.
Just not sure yet. The connectors are relatively cheap as well as the relay. The only unknown is the custom PCB. I'll get into that and post back once I have something more concrete. Thanks for the interest.
 
Is the PCB going under the truck near the transfer case or inside the cab? PM me so I can help you with some PCB design considerations.
 
Is the PCB going under the truck near the transfer case or inside the cab? PM me so I can help you with some PCB design considerations.
@BroncoHooves, it would go in the cab right at the TCCM in the passenger's side kick panel area. The only reason for the PCB is because the receptacle of the connector they chose is only available in PCB mount, but that's just as well since it makes the 20 pins easier to do vs. 20 crimped wires. I'll PM you shortly.

Thanks!
 
Here's the 2020 F-250 Platinum TCCM circuit diagram for CVH is anyone is interested:
CVH Circuit Diagram.jpeg
 
One other consideration that I just thought of would be the potential ramifications on the warranty. Can you please explain your thoughts on that? I'm very risk-averse and wouldn't want to jeopardize the possibility of having them void a covered repair because of the alteration.
With that being said I'm still interested. Thank you.
Don
 
Yes, I had thought about that some. Best I can tell, is if the module totally fails (which is 99% straight wire-through traces), the transfer case just can't be controlled and should stay in whatever configuration it was already in. Should the relay or the operational portions fail, just the hub locking will fail. All of that can be remedied by merely removing the module, and everything should go back to normal as we're not adding any voltage where it isn't already today but merely adding a relay on a single ping and controlling whether it's connected or not. Shouldn't be any different than putting the relay on the solenoid connector under the hood, aside from the other pass through connections.
 
Yes, I had thought about that some. Best I can tell, is if the module totally fails (which is 99% straight wire-through traces), the transfer case just can't be controlled and should stay in whatever configuration it was already in. Should the relay or the operational portions fail, just the hub locking will fail. All of that can be remedied by merely removing the module, and everything should go back to normal as we're not adding any voltage where it isn't already today but merely adding a relay on a single ping and controlling whether it's connected or not. Shouldn't be any different than putting the relay on the solenoid connector under the hood, aside from the other pass through connections.
While I was reading this my brain was going, blah blah blah, blah blah, blah blah blah. Just not good with this type of stuff. Sounds like you know what you're talking about though and the risk is next to none. Bottom line is if I have an issue with the transfer case and it has to go in for repair, just take the module off and plug it in like it was before. Thanks again.

P.S. I'm sort of like George Bush Jr and I'm not the sharpest tool in the shed, but I surround myself with smart people, then I process all of their opinions and make the best decisions from that. Kinda like he use to do.
 
While I was reading this my brain was going, blah blah blah, blah blah, blah blah blah. Just not good with this type of stuff. Sounds like you know what you're talking about though and the risk is next to none. Bottom line is if I have an issue with the transfer case and it has to go in for repair, just take the module off and plug it in like it was before. Thanks again.

P.S. I'm sort of like George Bush Jr and I'm not the sharpest tool in the shed, but I surround myself with smart people, then I process all of their opinions and make the best decisions from that. Kinda like he use to do.
No worries! I'm like that too, just with other stuff I don't understand. I'll be sure to post back once I have any updates.
 
This sounds super interesting, as I also have a 32’ RV. That being said, I don’t have any concept of the benefit 2LO would provide while backing a trailer. I’m not saying it does not exist, just that I don’t myself know what it would be like. For example, would it be more helpful when backing on a hill perhaps? Just curious!
 
I haven't experienced it myself, as my truck is still on order. . . That being said, if you search this forum for 2LO, there's a few other threads on it and the general consensus I get is that it's more torque/power and less speed potential with just as much steering capability. It was intriguing enough for me to attempt it, but without cutting anything, hence the rabbit hole I'm going down.
 
This sounds super interesting, as I also have a 32’ RV. That being said, I don’t have any concept of the benefit 2LO would provide while backing a trailer. I’m not saying it does not exist, just that I don’t myself know what it would be like. For example, would it be more helpful when backing on a hill perhaps? Just curious!
Yes exactly. For backing or pulling up a hill where steering is needed at some point during the maneuver. If you are in 4LO, the front hubs are locked automatically. This causes binding during steering. Not good for the tires or the drive lines. Back in the eighties, when I was a teen, I used to pull our boat out of the water after my dad drove it up on the trailer. He used to have me put it in four-wheel low but I didn't lock the manual locking hubs. I was able to creep slowly up the ramp, with little or no wheel spin and not have any issues with steering while driving on DRY pavement to the parking spot to secure the boat for the ride home. Works great except our trucks have automatic locking hubs so there is no way to engage the transfer case just to the rear wheels. Hope this helps.
 
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Thanks Don! That's enough to get me to proceed. I'll order a few connectors and work on the board and see where it goes. Might take a month or two, but I'll ping you when I have something and you can be a beta tester for me.

Would think Paul at SwarfWorks would be the man to talk to about this

 
I've got an old F250 7.3PSD that I swapped out the auto hubs with manual Warns a long time ago. I routinely will leave those unlocked and use "4 lo" in 2wd mode to slowly creep to back trailers uphill, up driveways, etc. Also good to run in "4wd" with unlocked front hubs occasionally to lube all the front items if one doesn't have routine opportunities to get offroad. It's super handy. For backing in "2 lo" it's slower, more controlled, and easier to keep things safe. It's also MUCH easier on the transmission. The reasoning back then was that tranny didn't like lots of long term loading in reverse - it would burn it up quicker than loading it in forward gears. So, thus the benefits back then somewhat translate to today. I just did the relay (normally closed pins) connected to up-fitter "4" mod this weekend on my 2022 F350 and it's working well.
 
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