2015 SR 4.6 2WD to 4WD conversion

So I have a 2015 SR 2WD and I bought a [not running] 2008 Limited 4WD; I'm planning to convert the 2015 to 4WD and need to know if anyone can confirm the 5.7 tranny will work on the 4.6 engine and ECU.

My plan is the following:

Move the tranny and transfer case
Move the Front ADD, CV joins and wheel knuckles
Install a 2015 4wd ECU and wire it for the transfer case actuator and ADD actuator
Reset the main body ECU so it "learns" about the new components installed

Possibly move the rear diff gears from the 08 to the 15 to match tranny, ADD gearing.

I'm keeping the 2015 for the rest of my life so trading is not an option for me but I want a 4WD.

 

I'm gonna go with no. It will not "learn" the new hardware. It's been programmed with parameters for specific hardware and specific combinations. The transmissions were not the same between the two engines either. Can you get all these parts to work together somehow? Maybe. Gonna take interface modules and lots of repining harnesses. Not worth it.

 

I found this document that is very encouraging; it states "A760E/A960E/AB60E 6 Speeds Drivetrains Are All The Same"

https://atracom.blob.core.windows.net/webinars/import/a760-ab60_comparison.pdf

Edit: the AB60 is the same layout but has bigger components, to account for handling more torque.

 

They are not the same. I do not concur.

 

Are they both 6 speeds? Yes, same. Are they identical and can be interchanged Willy nilly? Nope, not same. They share many parts and construction, but not all.

 

Ok, plan B; if I cannot move the 5.7 tranny into the 4.6 truck, does anyone have info on the A760E/F differences?

Is it just the extension housing that is different or is there a different output shaft to connect to the transfer case/drive shaft, depending if it's 2WD or 4WD?

If the output shaft is different, does anyone know if it can be swapped without taking apart the whole transmission?

 

Wow, that's pretty ambitious... Good luck.

So I'm curious... "I'm keeping the 2015 for the rest of my life so trading is not an option for me but I want a 4WD."

Is there a sentimental attachment to the 2015?

 

Well I really like it, but the main reason is I know it's in good condition. You can't but a V8 new anymore and I've had mine for three years and 50K miles and no problems. I looked around for a 4wd and they all looked beaten up under $20k and I didn't want to spend more than that.

The conversion is simply bolting parts that could have come on it from the factory!

 

Well, not that simple, but doable. Better off with a proper donor vehicle with appropriate matching parts though.

 

Ahhhh, gotchya.

I used to enjoy wrenching on stuff from the old days when you had room to work and could see the stuff you're trying to get to. (and I could lay under a truck without needing to go to the chiropractor the next day)
I look under the hood of modern vehicles now and go "Nope, I'll pay my guy to do that while I go surfin'!"

If you do it, take lots of pictures and post a write up!

 

I’m sure this is doable, certainly not plug and play, and I’m glad I’m not the one undertaking it, but I’m along for the ride!

 

I have done motor swaps when I was younger. Nissan 240sx with sr20det. I've help do 2jzgte swap into a Lexus GS300. I also helped friends do automatic to manual conversions. To be honest, I have never looked into doing a 2wd to 4wd conversion in a Tundra. But I don't think it's as simple as plug and play and bolting on 4wd parts. The ECU will not "learn" the new parts. I'm not saying it's impossible. While 2007-2021 share a lot of the same parts, some are different. I would try to find donor parts from another 2015 Tundra 4.6 (or at least a 2.5 gen)...the tranny, ECU, all 4wd front end parts , etc. You may also need the electronic on inside...dash, gauge cluster, switch, wire harness, etc If you're trying to use the parts from the 2008 5.7 it will make it more difficult. The wire harness may be also different in the 2008 5.7 vs 2015 4.6 I applaud you for wanting to attempt it. Please keep us updated.

 

Look up Cruzer’s rubicon build thread. Lots of great info you need about the front diff, t case, and transmissions. The 4.6 trans has different rations than the 5.7 trans I believe so they aren’t identical

 

While I have no doubt you can swap everything around, another option you might want to consider is you could do a divorced transfer case and then install the front components. Then your transfer case and differential will be their own isolated unit and not talk to the truck (either as a fully manual setup, or an electronic "manual" setup). It would require some fabrication skills to mount the tcase, though that might be inevitable with either path you go down. But you would drastically simplify everything else since you don't have to screw with the stock electronics, and your 4WD would not be based on what the truck wants to do (which anyone that has driven stick shifted tcase knows is far superior than the annoying electronic shit of modern tcases). Additionally you could customize the tcase to what you want specifically and get a much stronger one, lower gearing, more gear options, front dig, etc. if you wanted. And it doesn't necessarily have to be divorced, but if it was divorced you wouldn't need to attach to the transmission at all. Functionally it would be the exact same either way.

Food for thought.

 

Yeah, I looked into a divorced setup but I came across this non-running [bad ecm] 2008 Limited 4WD and I bought it. The engine has good compression so I'll sell it and recoup most of what I spent on the truck so the conversion is essentially free.

The ADD and TCase are the same parts and so are the front drive shaft and the cv joins.

I looked at the 4WD ecu diagrams of both the 2008 and 2015 and the 2015 is way more simple so I will use it and wire it to drive the actuators (tcase and ADD).

From what I've read, once I plugin the 4wd ecu to the CAN bus [and] reset the main ECM, the truck will be "converted" electronically to a 4WD, the dash will light up the 4wd lights to signal something is wrong with the tcase and ADD and once I plug them in, it will see them and use them based on what I command them to do with the 4wd switch on the dash -- still to be installed.

It's all theoretical though.

 

I think this is going to be one of those things you’re just going to have to dive in and troubleshoot as you go. I haven’t seen anyone doing this specific swap, so I doubt anyone on here has first hand knowledge of compatibility, but hopefully it works out for you and you can do a write up to help others navigate similar swaps.

 

It is all theory but if you shop for the main ECU for my 2WD and shop for a 4WD, you get to the same part number (896610CP13). If you look at the what fits section of the Toyota parts website for this PN, you see all models 2014 to 2018 both 2wd and 4wd use the same ECU.

Here is where resetting the ECU comes into play; when reset or installed new, it learns what is connected in the CAN bus and makes use of it.

Now can someone confirm this theory?

 

Update: It seems Toyota has customized the bellhousing of both the AB60 and A760E/F and they are both interchangeable. I got confirmation from another fellow Tundras.com member and he swapped a 4.6 engine into a 5.7 truck successfully and everything bolted right on and worked just fine.

So now I'm going to help my son fix up a 5-series he bought so he can lend it to me while I take my Tundra offline for a few weeks to install the front ADD, rear diff, transfer case, front and rear drive shafts, front CV joins, new front wheel bearings, electronics, etc.

Stay tuned!