I visually inspected the speed sensors and respective harnesses. Seem fine. I disconnected the wires from control arm / spindle when putting on the lift. Anything else I can check here based on your experience? All the ABS functions work well.

There’s an order to checking the ADD prongs with a multimeter, right? Do I need to remove the ADD off the diff?

unfortunately no. Mine also looked completely fine. Did you pull codes? Mine showed C1407 Open or Short Rear Speed Sensor RH. It was only after I replaced the harness and stripped the wiring on the old one to look at it, did I notice it was bad.

Sounds like I need to get my code reader going.

That won't affect shifting back and forth from 2 to 4wd. It will in fact cause all the Christmas tree issues when his skid module is disabled that he describes. Good observation. But we have determined that symptom is due to a communication error between a.d.d. and skid module. 🙏

No just the connector to start.

You don't need a scanner. You can pull codes which would be really helpful manually with what Toyota calls a sst check wire. A jumper wire In real talk. Right now at home within a few minutes. Get on that sh1t.

Mind to elaborate? I’m confused.

At the DLC you can jump terminals 4 and 13 with a jumper wire THAT FITS NICELY. *Carefully do not damage/spread terminals*. Turn key to the on position. The CEL, VSC, ABS, etc. lights will blink all your codes in a readable pattern. Different lights represent the category the code falls under. You can look up the procedure and how to read the blink patterns on the internet pretty easily.

I repeat
*CAREFULLY jumping the wrong terminals can cause electrical damage, don't f_ck up your DLC connector by pushing in or over spreading terminals*

Use the same caution with the add connector and examine it for related damage when you decide to begin testing the circuit..

I second the warnings above.

Make sure you're looking at the connector in the right orientation... last thing you wanna do is short a CAN Bus.

Thanks. Does this reflect the updated OBD port design used in the 2020 model?

Should be the same, the physical port and the large majority of its pinout is dictated by the SAE and the US regulations, Toyota hasn't really changed the pinn locations for their proprietary things as far as I'm aware.

They did in 2020. You used to be able to do a zero point calibration by sticking wires into the OBD port. No more.

Sorry, I should have clarified... the physical wires and their labels/functions are still the same. But you're right, it seems they scrubbed any mention of jumping pins for blink codes from the FSM; I hadn't noticed they did that. I really don't use anything besides the scantool, so I hadn't even noticed they made a logic change in that regard.

I think it may have something to do with the newly implemented J2012 DTC protocol. This expanded the way DTCs are coded and stored an include an additional 2 digits (a total of 7) for symptom/detail conditions. So codes like P0441 will now have another 2 digits after that to indicate a more detailed failure, i.e. P04419C (though there are no other detail suffixes for that code or a lot of the newer ones... so it didn't change that much).

The 4Runner doesn't seem to be using 7 digits DTCs at least glancing at the FSM super quick on lunch... but maybe when they started updating the OBDII protocols they programmed out the functionality to get blink codes and perform "manual" calibration modes? I don't see it written down anywhere, but I'll dig a little deeper later tonight if I have time. Either way... I don't see why you couldn't still have that functionality other than making it harder to diagnose/repair the vehicle without at least an OBDII tool... sorta scummy...

I think he may be right. Looks like the cg and ts pins were removed in 2020 to make it more difficult on DIY ers. Pin TC #13 is in the same place I believe??
Pin #4 is cg (chassis ground) or used to be.. so would jumping #13 tc to a body ground enter DTC check mode in the same manner as jumping pin 4 and 13 prior to 2020?.. I don't have the FSM for 2020 blackworks sounds like does though! It sucks because the manual way gives you every code. These free rental scanners won't. They won't even read abs codes for the most part..