Edit: I know how to use my locker, but it still won't engage. Update: I think it's the actuator

Edit:. I know how to use the locker. I have used it successfully many times

It got stuck engaged in August, and I eventually got it to disengage. Now it will not engage. I know how to get it to engage.

If anyone has had this particular issue and figured it out, please let me know.

There is a click in the rear differential when I attempt to engage or disengage it. But, that's it. @McSpazatron sent me a video of his, and the click is followed by the sound of something like an electric motor. I'm not getting the second sound.

I'll look at it more closely this afternoon or tomorrow and post anything I find.


Original post:

2019 TRDORP, ~85K miles.

In August, I had used the locker in some rocks, and then I disengaged it. But, once I got back onto pavement, it became apparent that it hadn't disengaged. I pulled into a gas station and was able to get it to disengage, but it wasn't easy.

This past weekend, I tried to use it several times, but it didn't seem to want to engage. I gave up trying, because I didn't want to have it engage and then be stuck again.

Has anyone else had this happen? I'm just curious how to go about diagnosing the issue.

I haven't really looked under there yet. I assume the only thing that I can really check externally is that the electrical connections are good. And, I have to assume that they are since I was able to get it to disengage the last time. But, I will probably take a look under there after work today.

Just curious if there's anything I can test without disassembling the differential.

I did change the fluid after the August incident, and the old fluid looked good.

Edit: if anyone has a link to any good videos or articles about servicing the rear differential locker, I'd appreciate that as well.

Edit: I'm not trying to get it to engage. I've used it a bunch of times, and it's never had an issue until this August. I'm trying to figure out what the issue is.

I'll ohm it out after work.

 

Did you check the actuator? You can take an ohm reader and check voltage, was it submerged in water or mud, the contacts might be corroded. Or simpler yet drive back and forth and in a figure 8 while trying the locker

 

I had to steer it back and forth to get it to disengage in August. I tried steering it back and forth to get it to engage this past weekend, but no luck. And, once I realized it was acting up I decided to stop trying.

I'll take a look at the connection later, and try to ohm out the actuator. I'll have to figure out how many ohms I'm looking for.

 

Alternative to figure-8s: jack up one of the back wheels and set it back down.

 

I'm not trying to get it to engage. I'm trying to figure out why it won't engage. It got stuck engaged in August, and I figured it was a fluke. But, now it doesn't want to engage. I've used it multiple times every year, and it never gave me a hard time until August.

 

I know mines a third Gen. But if I don’t engage locker for awhile you have to drive back and forth a bit and then it “loosens up” and engages, disengages faster.

 

Mine gets used regularly. I had a situation in August where I used it and it didn't disengage. Eventually I was able to get it to disengage, but now it won't engage.

 

Subscribing since I have a '19 that doesn't get the locker used as regularly.

Thought I'd read about this in the past so did some research. Mostly 3rd gen forums (not sure if e-lock or vacuum) saying time and figure 8's to get it to lock is normal because teeth need to line up. Interested to see what solution is found.

Sounds like checking electrical current would be a good first move but to me it seems more like a sticky mechanical feature causing the issue.

Any light indicators on the dash telling you it's trying to engage? I'd say that may rule out an electrical issue unless it isn't recognizing it engaged. If electronics are saying it's trying then the issue may be mechanical or the relay back

 

The light flashes when I hit the button. It just doesn't want to click in. I've used it dozens of times without any issues before August. You can generally hear it when it engages and disengages. What was weird is that the computer thought it had disengaged in August when it got stuck. I didn't realize anything was wrong until I got back on pavement.

I have to get underneath it later this week and look at everything. I was hoping someone knew which prongs to test on the plug, and what impedance I should have. Or, if there was a procedure to inspect and test the actuator.

 

So as a system engineer, this would make me think the electrical connections are fine but there is a mechanical component in between the electronic actuator and mechanical component that isn't communicating correctly. Can't verify or troubleshoot any more without the vehicle unfortunately but if the system reports it's engaged/disengaged without the correct feel I'd say it's a stuck mechanical component sending a false signal. Maybe tap with a rubber mallet to minimize damage but feel if something moves?

Edit: if the system (computer) reports that it's disengaged then the eletrical circuit seems complete. There is probably no electrical component in the system verifying that the mechanical component did what it was supposed to do, only that the system could verify that the signal was received and completed the signal message

 

Although not very scientific, but you place the vehicle in 4L and then have someone you trust activate the locker switch while you lay under the truck with your hand on the locker actuator. You may feel something which would tell you that at least the electrical control circuit is working.

I don’t know whether the rear locker uses an actuator or if it’s an electromagnet.

Just make sure the vehicle is in park and the parking brake is on.

 

I thought about tapping the differential to see if it might free it up. To clarify, I eventually got it to disengage in August, but now it doesn't want to engage.

I didn't try very hard to get it to engage, because I have never had to mess with it much before. And, I figured if there's a problem, I'd rather be stuck open than locked.

 

Agree with that logic, see the edit in my previous post about system verification (this is a theory as I don't know what toyota implemented)

 

Good idea. I might have a buddy stopping by this weekend, so I can try that if I don't figure it out before then. I'll probably end up putzing with it Saturday morning, because I'm driving further for work this week and there's not much time for anything after work.

 

I'll admit that I know very little about these lockers. That's why I come here for ideas.

 

You have a 19’? Correct? If you’re not at 60k miles, you should be able to utilize the powertrain warranty. That would be the most economical way to go.

I haven’t come across many post regarding issues with the factory locker so it may just be dumb luck.

 

Come on, I've learned so much from you on this forum. If I can help you troubleshoot I feel like the man .

I have the locker in a similar '19, I'm just spitballing at how I think they work based on my limited knowledge

 

I'm at 85K, last time I checked.

I haven't really heard of any issues, either, aside from those who have difficulty engaging them.

I'll definitely post up here as soon as I figure anything out.

 

Dang, I guess I need to get out more often. Mine is a 2018 and I just hit 26k on the odometer last week.

 

I'm definitely getting my money's worth out of it! I don't even drive it to work, either.

 

Electromagnet and all internal. There is pretty much no moving parts other than the plunger and dog clutch that get actuated by the solenoid.

What's very odd here is that you found it remain locked but the light when out. The light won't go out unless the switch is physically moved to the unlocked position which should only occur if the dog clutch moves to the unlocked position. Are you 100% sure the diff was actually locked? If it was locked and no light then you may have an indicator switch problem which might allow the system to get into states it's not supposed to be in.

When you try and engage it now and it won't, does the light flash like it should? Have you confirmed that the diff is or isn't locking or are you going by the light?

What I'm getting at is you need to make sure to isolate what's mechanically happening (diff is/isn't locked) versus what is electronically indicated (diff lock light is off/on/flashing). Once that's settled you'll know whether to trouble shoot the indicator switch circuit, power circuit, or the internal mechanical parts.

I also assume no work has been done on or near the diff lately?

 

There are several electronic components in the system that come into play. In the transfer case, you have a 4L sensor switch. This switch grounds, or is supposed to, when you are in 4L, which then allows voltage to the actuator via a trigger, namely, the RR DIFF LOCK button. This engages the diff lock actuator, which is a spring controlled slide mechanism. When engaged, there is a sensor on the actuator which grounds and tells the system the RR is locked. If that sensor is bad, the diff lock light on your dash may blink, even if the rr is locked.

Most common cause of RR diff lock issues is buildup on the 4L sensor inside the tranny. Regular engagement of all the system components will ensure this doesn't happen. You can sometimes fix an unresponsive 4L sensor by the following procedure:

With the 4Runner running, parked on level ground, with the emergency brake engaged, and the transmission in neutral, rapidly shift the transfer case from 4H to 4L 30 times.

Also, in order for the locker to engage, it requires there to be some slippage, so turn the wheel slightly left and right while driving slowly forward to allow the diff to lock.

But since OP isn't having an issue getting the diff to lock, you are likely sealing with some corrosion in the spring mechanism inside the actuator. The grease used in there can get hard and waxy with time, or any water or condensation can cause corrosion to prevent the spring from moving freely. I think your best bet is to so somewhere that you can engage and disengage the locker multiple times in succession. Hopefully once it's used to moving again it will not get stuck.

 

That's impressive. I was putting 22k/yr on mine for a while commuting but starting working from home again recently. Have about 50k on my '19, hoping to turn it into a dedicated SUV rather than daily driver

 

How's your differential oil? I know how much you like splashing through water and mud

 

Mods, please forgive the external link.

https://www.fjcruiserforums.com/thr...erational-rear-diff-lock.432729/#post-6154497

I highly recommend this read in understanding the diff lock system.

 

Yes, as indicated by the tires chirping around a turn. I was no longer in 4wd.

Yes, it flashes, but doesn't go steady. As I mentioned, I didn't try any tricks to get it to engage because it's never been difficult before. And, I didn't want to coax it into engaging only to be stuck driving it home 200 miles with the locker engaged.

 

Definitely not a problem.

I've never had any trouble engaging it before.

Maybe I'll try putzing with it in my driveway this weekend. If nothing else, the neighbors will be amused.

I changed it after the situation in August. It was fine. I was concerned about water intrusion, but there was no sign of any... Surprisingly.

 

Instead of going by the light, let it flash and then physically confirm if it's locking. If it is, you most likely have an issue with the indicator switch or circuit since you've both known it was locked with no light and then engaged it with a flashing light.

Most of the random issues that have come about with these lockers have revolved around the indicator switch after it's been messed with or externally damaged. Do note that the switch is not supposed to come out with the carrier still installed in the 3rd member because it "hooks" over the indicator plate. Having said that there have been some guys that have had success getting the switch in and out without removing the carrier or 3rd member.

 

If you frequent deep water, make sure you extend not only the diff breather, but also the actuator breather up higher!

 

I can usually tell when it locks. There's usually a click as everything lines up. I'll definitely try engaging it again and confirm whether it will engage or not.

I keep planning a breather relocate, but if I haven't gotten water in the diff yet, it's probably not going to happen.

I've never heard of anyone relocating the actuator breather. I didn't even know there was one.