NEED HELP 2WD to 4WD conversion the old school way

WonderboyT

Original poster
Member
Dec 6, 2018
6
Jacksonville, FL
Hey guys, I know I am probably beating a very, very dead horse, but just trying to think outside the box. My dad asked me, so I'll ask this community...is there a way to run 4WD the old school, manually/mechanically actuated way to bypass all of the electrical headaches of doing a 2WD to 4WD conversion (aka not have to worry about computers and wiring harnesses, etc? Now, I know I will get a million questions asking why I would want to do this and why I wouldn't just buy a 4WD trailvoy on the cheapside, and the simple answer is this...there is no way I would ever convince my wife to let me trade what I have for what I want. I know they 4.2L oil pan is already configured for it and I would obviously have to buy all the necessary parts, but has anyone ever attempted a setup like this or know whether or not it can be done? Thanks in advance and shoot straight with me. I've read a lot on the forums about doing a swap, but it seems the lone setback/money pit is the electrical side of the swap.
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
Just so I don't repeat myself:

Converting from 2wd to 4x4 is doable but will require a lot of custom wiring to make it work or replacing the wiring harness. You will need everything from a donor truck including the rear and front driveshafts, front diff, intermediate shaft, disconnect and axles. If swapping the wiring harness, you will also need the transfer case control module and a reflash of your BCM with the proper software to enable it. If going the custom wiring route, A4WD will not work.

A electronic-less operation of the NP226 is possible by understanding its operation. The disconnect can be replaced with the AWD version that is always connected. Or a 4x4 version can be simply controlled using push buttons or a DPDT momentary switch. Therefore all you will need is to control the encoder motor on the TC. I think this could be done with a series of relays and push buttons to operate it. To engage 4hi should be fairly simple. 4lo is another story as this needs a bit of a sort of finesse to get it to engage and I'm not sure how the TCCM normally interacts with the encoder motor as the truck has to be moving slightly to engage and disengage.

Somebody correct me but I don't think there is a mechanical TC that can be swapped is as it has to have the exact same dimensions and orientation as the NP226 to be able to connect to the front diff.

And I also forgot that you will have to replace the tranny's tail piece and output shaft, requiring tearing into the tranny or replacing it with a 4x4 version.

Sorry to say but, your best bet is to just trade it in for 4x4 model. Just tell the wife it would cost more to convert it.
 
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WonderboyT

Original poster
Member
Dec 6, 2018
6
Jacksonville, FL
Mooseman, thanks for the quick response and good info. Just thought I would ask the question, but as you pointed out there are more headaches than just the electrical one. I've seen a lot of different answers on other forums, but this answer has been the most helpful.
 

HARDTRAILZ

Moderator
Nov 18, 2011
49,665
If you dont mind lifting to get it under there, you would be better off going really old school and slapping a solid front axle under it. Forget all the electric crap. Its the only way i would swap one to 4x4.
 

WonderboyT

Original poster
Member
Dec 6, 2018
6
Jacksonville, FL
I plan on building up an engine from the ground up and putting a Monster tranny/TC package on it, so I plan on spending a little money, but spread out while I collect parts. With that said, if I get an engine from a 4.2L 4x4 along with all of the driveshafts, TCCM, front diff and axles while grabbing all of the electrical harnesses I need, the only thing left once it's all together would be to flash the computers for them to relearn everything, right? I fly helos in the Navy, so I'm no mechanic. However, it seems pretty straight forward what I would have to do. I'm just trying to find out what aspect I am missing with all of these conversations. Because I planned on updating literally everything and spreading out the costs while I collect parts, that's why I thought maybe I could get away with a conversion rather than spending money on a used 4x4 only to update everything with all of the aforementioned parts. Once I have everything collected and ready to go, I'll grab my dad and take a long weekend to throw it all in. Either way, I'm intrigued by doing something not many have attempted.
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
You would practically need someone with a Tech 2 to flash your BCM. That will also involve the VATS to relearn your ignition as well as a security relearn. Or if you grab the everything from the donor, including BCM, TCCM, steering column/security module and PCM that has the same options as yours, you might be able to get away with it but the VIN in the BCM will not.match what's on your vehicle.


Apart from lighting the light in the cluster when the TCCM is in trouble, I don't know what other interactions it has with the BCM. It might work on iits own without the BCM programming.

Edit: scratch that. Just remembered that the TCCM uses the speed sensors for the A4WD.
 
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