What is wrong with this (rear differential) picture

Friday night I was going down the highway and the rear locker light started randomly flashing (shortly after going over a hard-ish bump). After a while it would flash constantly and stop for a while.

Since it did not feel like the locker was actually engaged, I drove it home and unplugged the battery overnight to see if resetting the ECU would clear it. No such luck. It does not come on right way while driving now, but after a bout 10 mins it will start flashing and then go out for 5-10 mins before flashing some more.

With the diff cover off I had someone engage and disengage the rear locker while I watched inside the diff. I can see thin disk (green arrow in pic below) move a little when it engages and the dash light stays solid. When we hit the switch to disengage the locker, that thin disks moves again, but the dash light keeps flashing. I can then put it in 2 Hi and drive around and can tell that the locker is not engaged, so I know it is not getting stuck in either condition.

Here is a pic of the inside of my rear diff:



And here is a pic a friend of mine sent of his (can't get it to post in line here at work, so it's attached below)


And finally one I found off the internet:



In my pic and the one from the internet, the triangular part with the tab on the end of is not engaged with the slot on the ring to the left of it (blue arrow). In my friend pic it is. Can anyone tell me if the tab should be in that notch and if so, under what conditions?

If you look at the red arrow, it also looks like mine might be bent as well, any thoughts on what might cause that??

Finally, here are two short (couple of seconds each) vids of how things move about in there (sorry the vids are sideways from my cell phone):

Video 1

Video 2

Should that ring with the notch in it rotate that much back and forth?

Thanks for your time and any help you can give me.

Just to make sure, did you double check the plunger - the sensor that should be making contact with the dog clutch (thin disk that moves in and out). That's ultimately what sends the signal to your dash and lights it up and turns it back off.

Thanks for the reply. Short answer, no as it all seems to be working other than the light still flashing. I'm actually not 100% sure there to find the plunger is it #2 in this image:

View attachment 135120


I hope that attachment shows up, I stole it from another thread here.

Z Hunter said:

Thanks for the reply. Short answer, no as it all seems to be working other than the light still flashing. I'm actually not 100% sure there to find the plunger is it #2 in this image:

View attachment 135120


I hope that attachment shows up, I stole it from another thread here.

Click to expand...

Right, if everything is working fine other than the light, your problem is most likely an issue with the plunger. It sits far back in your diff housing and is located at the top near where the plug goes in. It kind of looks like a mushroom and the bottom of the hat should be making contact with the dog clutch.

Okay thanks. Now that I know were it is at (inside of where #2 in that diagram), I'll give it another look. And to make sure I got this correct, that plunger should be touching the dog clutch at all times (engaged and disengaged)?

Any thoughts on the notched ring (do you know what the name is for that?) rotating like that?


Thanks for the quick help on this!

Z Hunter said:

Okay thanks. Now that I know were it is at (inside of where #2 in that diagram), I'll give it another look. And to make sure I got this correct, that plunger should be touching the dog clutch at all times (engaged and disengaged)?

Click to expand...

Yes, it's a spring loaded sensor that moves in and out with the dog clutch. It will be making contact with the clutch at all times when properly installed. If you just had new gears installed, your installer most likely put this on the wrong side of the clutch as that is a common mistake.

Any thoughts on the notched ring (do you know what the name is for that?) rotating like that?


Thanks for the quick help on this!

Click to expand...

Sorry, on my phone and it's hard to see things. I can try to give this a better look later.

No gears here, it's all stock and nothing was done to/around the differ or sensor connectors. Simply driving down the road

Z Hunter said:

No gears here, it's all stock and nothing was done to/around the differ or sensor connectors. Simply driving down the road

Click to expand...

Hmmm - well, the only thing I can think of is that your dog clutch is no longer moving in and out as much as it needs to get the sensor to turn off the light. Depending on how much you've used your locker since getting your Jeep, I have seen where the internal components start to crack and the wave spring is no longer able to push them as much as they need to move. of course, it could just be something stupid like a loose connection. Good luck.

Thanks again.

Anyone know how much that dog clutch should move?

Z Hunter said:

Thanks again.

Anyone know how much that dog clutch should move?

Click to expand...

About 1/4" or so.

Just to close out this thread...

After changing the diff oil and cleaning out the sensor with compressed air, my flashing light issue has gone away. I still have to figure out what to do about the tab/notch engagement problem, but it does not appear to affect the locker working in any way. The rear locker does take longer to disengage then the front, but I don't know if that is normal or related to the tab/notch in any way.

Z Hunter said:

Just to close out this thread...

After changing the diff oil and cleaning out the sensor with compressed air, my flashing light issue has gone away. I still have to figure out what to do about the tab/notch engagement problem, but it does not appear to affect the locker working in any way. The rear locker does take longer to disengage then the front, but I don't know if that is normal or related to the tab/notch in any way.

Click to expand...

Honestly, I think you're barking up the wrong tree with the tab/notch thing. Factory lockers are weak and I went through 3 of them early on before finally making the switch to ARB's. Hard use will cause the internal components to crack and this will make it harder for the wave springs to move them around. The new oil might be helping with this for you now though.