2010 TRD OR Pre-Runner diff lock issues

Lately I've been having issues with my rear diff lock engaging on its own while I'm driving on the highway. Last time it happened was at over 60 mph, I think after hitting a bump of some sort.

Initially, I didn't know if it was just the lights coming on to indicate something else, but the CEL doesn't light up, and nothing flashes; I just get the rear lock indicator, DSC OFF, Traction Control Off, and ABS lights on the same as what happens when I activate the lock deliberately. Also, I was able to hear the rear inside tire chirping on a corner (low speed) that I had to take in order to get to a safe place to turn the engine off and re-start which seems to be the only way to clear the condition, since cycling the RR DIFF LOCK button on the dash hasn't tricked it into releasing so far.

Has anyone else ever seen/heard of this happening? I'm probably overdue for replacing the oil in the rear end, but have the breather relocation mod done, and wouldn't think there's any water in there. Some metal shavings in the oil are possible since I think I have some wear on the pinion gear (rear end howls above 40 mph), but the magnet on the drain bolt should be keeping that out of the way.

 

That's interesting, I wonder if there isn't something going on inside the 4wd ECU. Would be worth popping it out and taking the cover off to investigate.

https://www.tacomaworld.com/threads/4wd-system-operation-help-thread.742420/

 

Would a PreRunner have a 4WD ECU? Without 4WD, there's no lockout for the rear E-lock, so I'd assume it can just be run off of an on/off switch. I wouldn't think that a loose connection would cause a false "on", but maybe a worn or chewed on harness could lead to a high-volts short?

Between this and the ring/pinion wear I might just use it as an excuse to swap for an air-locker anyway, then I can keep it completely disabled by just not powering up the compressor.

 

Pre-runners with a Diff Lock still have a 4wd ECU, it just doesn't have the components for the 4wd stuff.

 

Wiring Diagram.

 

Sorry, I never heard of this problem.....but how does the elocker solenoid engage when the rear end is spinning at a vehicle rate of 60mph?

When I engage my RR Diff lock, I have to be at a complete stop to activate. And then you'll hear some engagement noise, etc...

I guess I would expect some sort of failure if RR Diff Lock was engage at a high rate of speed.

The elocker motor isn't hard to remove. Maybe pop it off for a visual check?

 

I've got no idea how it's possible to engage at that speed, especially considering the difficulty I've had sometimes getting it to engage when I'm stopped and needed it on a trail.

I'm assuiming the fact that I was moving in a straight line and the freeway only had a couple of very gentle curves to it before I managed to get off is the reason why it didn't blow out my rear end though. I wasn't actually sure that it had really engaged or if I was seeing some kind of false indication on my dash lights until I needed to take a corner (at 5 mph) after getting off the freeway and heard the chirping from the rear-inside wheel to prove that the diff was actually locked at that point. Usually if the system is activated but the lock isn't engaged, the light for the diff lock flashes, and the times this has happened it's been steady.

 

I'll have to do a little deeper dive on this, but looks like the ARB air-lock with a one-chamber compressor is a little bit less expensive than the Toyota OEM e-lock replacement. No idea about the ECUs.

Either way, I'm assuming installation would be about the same, and I'm sure I'd save time or money or both by combining that install with the ring/pinion replacement by not having it all come apart twice.