SOLVED: 2015 TRD OR Stuck "Halfway" in 4x4 (4LO and 4WD flashing nonstop, NOT the ADD)

On a hunch, and against everyone's advice, tore straight into TC actuator and found as below

Full of water, also note the completely destroyed traces.

Going to take in to my office now and see if one of the electronics guys can help me restore the traces with solder and flux

 

Oh the perils of trying to diagnose a mechanical problem through a free, public forum..

Been here for a few years now and find people make good faith opinions 99.999% time.

Good luck! Hope you’ve found the root of your problem

 

Hehe, thanks for the comment. I do have a bit of background in engineering, feedback systems and control, etc so it was a bit if an educated guess. Judging by the pictures posted, it was a good guess...

 

Another update, contacts now "repaired". Time to reassemble...

 

Good sleuthing. Hope it solved the issue.

 

It's pouring rain right now or I'd go piece it together and test it. Soldered the front ADD while it was out

At least I've had an excuse to drive the SAS Chevy all week. Also, never doing a SAS again...

 

UPDATE

Works beautifully! I RTVed the ADD housing while it was out too

Loaded the soldered traces with dielectric grease. Really, they are patches of solder wick bridging what was left of the metal, and covered in solder.

The solder "hack job" of rebuilding the traces works well, and goes in and out of all positions 2HI, 4LO, 4HI with no issues! I'm going to keep an eye out for a new TC actuator at the junkyard, but for now, I can't complain. And I now have a better understanding of the system, should it act up in the future before I replace. Thanks for the pointers along the way!

I suspect this vent line has been disconnected since I purchased the truck, and in using it like a truck, I got it full of water. Certainly had a lot of muddy water inside. But the vent line wasnt just pulled off, but rather split at the end. Not a bad idea to check yours to make sure it's not split too ..

 

Did you do anything to get the gear contacts aligned? The following post seemed to be trouble if not aligned correctly.

 

I very carefully opened it and didn't rotate any of the moving parts, and put it right back together. No problems.

It's pretty intuitive once you stare at it for a while, how it works. I just made sure to pull the shift rod back out to 4hi before putting it back on

 

Update - still not 100% working properly. If I hit a good bump I get a 4x4 light flashing, intermittently. When I go to shift 4x4 nothing happens, just flashing light, and since TC shifts first, I feel like the problem is there somewhere. I feel like I have the thing clocked one or two teeth off on the gear, because I can always measure continuity on the motor/feedback pins, so it is making an electrical connection. Haven't messed with in a few weeks. Never did find a great bulletproof guide for setting the timing properly directly related to Tacoma, but found some guides for Tundra and 4Runner (theirs are even more complicated!) that seem promising. Just haven't had time to mess with it.