That's awesome please update on this when you are able to do so. Also, post pictures of your switch setup in the cab...I assume its still a switch engagement?I guess this could go into the driveline section, but to me it is definitely a performance mod.
Those of you with supercharged trucks and those with stock trucks in cold/snowy climates know how hard it is to get any traction in 2WD on take-off. I have an S/C truck in Canada, so I find that most of the time, if I want to race somebody, I have to quickly shift it into 4WD, otherwise most guys easily get a jump on you. That is all fine and well, until a corner comes up and you start running a risk of damaging your driveline on dry pavement. Also, once you kick someone’s butt, you are likely going much faster than 60 mph, so now you are stuck in 4WD, and if you are on a highway, it is not very convenient to slow down to shift back to 2WD. Even during daily driving, when there is a lot of snow/ice in the neighborhood, I always use 4x4 to get out, and then once you hit the plowed road, you have to switch back again, so another inconvenience.
For these reasons I have been wanting to add AWD option to my truck for some time now. I have seen a guy named BJowett on the forum who installed a Landcruiser T-case into his truck and he was my inspiration. Finally I had a few bucks in my pocket, and after doing my research, I ordered the transfer case I wanted. I decided not to go with the JF2A transfer case found in the Landcruiser and the LX570 because it is a full time transfer case with no option of 2WD, so instead I went with the Torsen LSD equipped multi-mode JF3A t-case found in the 2008+ Sequoia. That transfer case has all the options you can ask for: 2HI, 4HI free, 4LO free, 4HI lock and 4LO lock. So now, when I am driving somewhere in the summer on the highway, I can have it in 2WD and save on gas, if I am driving in winter or wanting to race somebody, I can put it in 4HI free, and when I go off-roading I can lock the center diff and have it in 4HI lock or 4LO lock.
I installed the setup yesterday and in the process found an unexpected hurdle. I expected the t-case to be a direct bolt-on, except that after the installation I realized that my front driveshaft was now too short and the rear was too long. Even though the cases look identical, the Sequoia one is 1¼ inches longer that the Tundra one! So I had to drop off my rear driveshaft at the driveline shop to have it shortened by that amount in order to be able to fit it in.
I was able to reuse the front shaft. I took it out, removed the boot and measured the length of the sliding yoke spline to be about 3¾ inches. Once installed, I still had 2½ inches of the splines engaged, so I reinstalled the boot and drove it home in FWD (4HI lock with no rear driveshaft lol). All I can say is there is a reason they don’t make FWD cars with 600 ft-lbs of torque! That thing torque steers like crazy when you step on it. Today I got the rear drive shaft back and installed. The truck drives AMAZING. On a side note, coming home from work after the install (in AWD), I saw my buddy at the lights and spanked his lightly modded Subaru STI from 0-60 mph by a couple car lengths. Had I been in 2WD, he would’ve easily had me on the launch, but I pulled out ahead right away!
So here is what you need to make this swap happen:
A 2008+ Sequoia T-case. I got mine from a wrecker from a 2008 model with 80000 miles on it.
A Sequoia 4WD ECU. I bought a new one for a 2009 model. For some reason the 2008 and 2009 part numbers and wiring diagrams were slightly different, I took a gamble with the 2009 one and it is working fine. Probably the 2008 would work just as fine too. (PN 89533-0C022)
A Sequoia center diff lock switch – fits directly into the Tundra dash. (PN 84725-0C130)
A pigtail for the 4WD ECU wiring harness since the Tundra harness does not have the center diff lock wire going to the ECU. (PN 82998-12870)
Have your rear driveshaft shortened by 1¼ inches and rebalanced.
Ideally, have the front shaft lengthened by the same amount. A Sequoia front drive shaft might work too, but I don’t know that for a fact, possibly the front diff flange or position in relation to the t-case might be different. I will get a buddy at Toyota to measure one for me when he gets a chance. As mentioned, I reused the Tundra front shaft, but it lost about 35% of the spline engagement from what it is stock. I don’t think it will be a problem considering how much beefier those splines are than the ones inside the transmission for example.
Remove drive shafts.
Remove stock T-case.
Send your drive shafts out to get shortened/lengthened.
Install Sequoia T-case.
Install modified shafts.
Swap the 4WD ECU (on the right side behind the glove box).
Install the center diff lock switch in the same spot as Sequoia has it.
Install the pigtail wire into pin 12 of the large 4WD ECU connector.
Wire that pigtail to ground thru the center diff lock switch.
This worked fine on a 2008 Tundra, I would ASSUME it will work fine on all 2007-2013, but no guarantees. I don’t think this will work on 2014+ since they use a totally different transfer case and transfer shift actuator.
Now, when you shift your truck to 4HI, it will be in 4HI free (AWD) and then once you shift the transmission into neutral and hit the center diff lock switch, it will be in 4HI locked (4x4).
I am still waiting on the center diff lock switch to come from Japan, so for now I used a generic switch from my parts bin. Once the proper one arrives, I will have fully stock integrated look. The other thing I haven’t done yet is install an LED that would show when the center diff is actually locked. On the Sequoia, the 4WD ECU tells the cluster ECU thru the CAN bus to turn the light on. The Tundra cluster does not have the center diff lock light, so the only way to integrate it would be to buy a Sequoia cluster, and I am not willing to spend money on that at this point. I will wire a separate LED into the signal from the center diff lock limit switch in the transfer shift actuator in the next couple of days and post an update.
Overall cost of doing this as well...ok not that I can afford it, but its nice to dream LOL.