Followup to my poor diagnostics on the rear locker failure I had a few weeks ago...
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Well, continuing on with my history of stumbling around blindly on this issue, turns out the locker was NOT working properly after replacing the harness with some broken wires. I merely assumed it was because it was making HEALTHY sounding actuation noises on both lock and unlock. Back and forth. But it was miserably cold out, and I didn't bother to jack up a wheel and make sure it was actually locking and unlocking.
Turns out, it wasn't actually locking. It would make noises and move, but only for a short period, stopping short of locked. Then (from the sound) it would unlock fully when the switch was turned off.
Argh, waited until a slightly nicer day (still cold, windy, miserable, the 4Runner doesn't fit in the garage so this is done outside) and took out the locker.
Long story short - it turns out that what I was doing by jumpering 12V to the M1/M2 wires to manually lock and unlock it is VERY RISKY. The actuator, when actuated by the locker ECU, which looks at the limit switches inside the actuator, only tuns about 1/3rd of a turn. Far lass than I thought/assumed (because it has a full, round gear both inside and out, most of that isn't used!).
When jumpering it manually, the actuator will move further, almost a half turn, until it hits some mechanical stops. And apparently, it can move far enough to get past the limit switches (contacts sliding on a metal plate with holes in it) to get past where the locker ECU thinks it should be. So the locker ECU tries to lock, sees something from the limit switches that says it's already locked, and it immediately stops trying.
This certainly wasn't clear to me underneath the car. I just took it inside the house and messed about with it on the kitchen table where it was warmer. And tested my locker and the new locker by jumpering the M1/M2 wires. Turns out the new locker did even worse, it jammed and wouldn't move after moving to the mechanical limit one single time!
Anyhow, after taking it apart and looking at how it works, we figured out how the limit switches worked, and how they 'logically' limit it to a much shorter range. And repositioned my locker, and the new locker that I'd jammed, and under the car, plugged into the car harness, saw them both turning the proper 1/3rd turn back and forth. My well used one made some slightly less good noises, so I put the new one on. Made sure the diff was unlocked, repositioned the actuator back and forth a couple of times, to unlocked, and installed it. Wheel jacked up, not it is FINALLY locking and unlocking properly again.
Sheesh, what a confusing long fiasco on my part. It was a quirky failure, compounded by limited diagnostics (cold and miserable outside) and me firing off the parts cannon too quickly.
But yeah, main takeaway, manually jumpering the actuator can leave it in a position that it can't recover from, and requires removal, partial disassembly, and manual repositioning.
Almost enough to make someone want to buy one of those cable actuators, lol.
But srsly, if I'd spent the time, jacked up a wheel, and done proper diagnostics, I could have figured this out on day one.
