Rear Locker Issue

[Phljeeper]

I am hoping someone can provide some recommendations for me. I have a 2020 JTR with about 42k miles on it. A couple weeks ago while driving on the highway my rear locker showed it engaged (on its own). I know it isn't supposed to engage while in 2wd or 4 high but it seems like there was an electronic issue causing this. Pushing the off button didn't change the state just put it to blinking but unable to disable. Thinking it may actually be locked I pulled over and jacked up one rear tire which spun freely leading me to believe the locker was actually unlocked so I pulled the locker plug from the rear diff which dumped a bunch of water out. In doing research I found this to be an issue others have encountered and Jeep seems to be replacing the entire rear end to resolve. Unfortunately I am running 4.88 gears so Jeep wont warranty the issue. To make things worse when I picked my Jeep up from the dealer yesterday thinking it was at least drivable and unlocked the locker seems to be locked and unable to unlock. So now I am stuck locked at the dealer unable to drive my vehicle home and they are refusing to work on it due to my aftermarket re-gear (which BTW was done 2 years and over 20k miles ago). Any suggestions? Running the bypass cable I have seen from Z Automotive that other threads recommend seems like it just sends a signal back to the Jeep to ignore the bad sensor. My fear is that would potentially allow the locker to remain engaged but the Jeep doesnt know. Am I misunderstanding the bypass?

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[dcmdon]

A couple of questions.

Why do you think you can't drive it home with the rear locked? You most certainly can. I wouldn't make a habit of it, but it won't hurt anything for a one time shot.

Once you get it home you can troubleshoot properly to try to get the rear unlocked if it is in fact locked.

I would want to know how the rear locker works. In the absence of a signal (wire pulled) does it unlock or lock? If we assume it unlocks (you need to confirm this) if it remains locked when the wire is pulled then you have a legitimate mechanical problem and you should bring it to an independent shop who can fix things.

If the locker unlocks when you disconnect the wire, then you have an electrical issue. I don't know the troubleshooting steps but I would test for a signal (I don't know what the signal is. 12v hot when on??)

Given all this I suspect that the rear diff isn't really locked and it is just a bad sensor. I'd try the Z automotive "fix" simply because people drove for 100 years without diff lock indicators. I suspect your system actually works fine it just is confused. No harm will be done if you accidentally leave it locked. Running straight it will work perfectly. When you make a turn it will bind. You will call yourself a bunch of names and you will unlock it. No harm done.

Finally, I think it is fair for the dealer to deny this warranty claim. The shop that installed your gears had the entire rear end apart. The fact that water intrusion seems to be the source of your problems means that that shop probably didn't put it back together properly. Or at the very least some part of the system that keeps water out failed when they put it back together. Either way, not Jeep's fault.

 

[Phljeeper]

Thank you for the quick reply. I guess I made the assumption that driving highway speeds with the rear locked would cause an issue but I am not actually sure. Glad to hear you feel it would be ok. I am only 5 miles from the dealer but would be driving at 60 mph. Also good suggestions on what to check, that would be my approach and was my approach when this issue first occurred. I tend to agree that trying the Z Automotive may be a good next step and I guess if any harm was done then the result is still the same as the dealer is saying which is to replace the rear (although not my desire for obvious cost reasons). As for the dealer warranty, my view is that with the common issue being the sensor due to water intrusion with or without a gear change the issue doesn't seem to be related to the aftermarket gear swap. But I agree, that I don't know for sure. If the water intrusion was inside the diff that is a different story but it seems to be at the sensor which unfortunately Jeep doesn't want to touch either. I do see the gray area on this but its frustrating that the dealer is just saying no coverage due to gears instead of troubleshooting first.

A couple of questions.

Why do you think you can't drive it home with the rear locked? You most certainly can. I wouldn't make a habit of it, but it won't hurt anything for a one time shot.

Once you get it home you can troubleshoot properly to try to get the rear unlocked if it is in fact locked.

I would want to know how the rear locker works. In the absence of a signal (wire pulled) does it unlock or lock? If we assume it unlocks (you need to confirm this) if it remains locked when the wire is pulled then you have a legitimate mechanical problem and you should bring it to an independent shop who can fix things.

If the locker unlocks when you disconnect the wire, then you have an electrical issue. I don't know the troubleshooting steps but I would test for a signal (I don't know what the signal is. 12v hot when on??)

Given all this I suspect that the rear diff isn't really locked and it is just a bad sensor. I'd try the Z automotive "fix" simply because people drove for 100 years without diff lock indicators. I suspect your system actually works fine it just is confused. No harm will be done if you accidentally leave it locked. Running straight it will work perfectly. When you make a turn it will bind. You will call yourself a bunch of names and you will unlock it. No harm done.

Finally, I think it is fair for the dealer to deny this warranty claim. The shop that installed your gears had the entire rear end apart. The fact that water intrusion seems to be the source of your problems means that that shop probably didn't put it back together properly. Or at the very least some part of the system that keeps water out failed when they put it back together. Either way, not Jeep's fault.

 

[hjdca]

I am hoping someone can provide some recommendations for me. I have a 2020 JTR with about 42k miles on it. A couple weeks ago while driving on the highway my rear locker showed it engaged (on its own). I know it isn't supposed to engage while in 2wd or 4 high but it seems like there was an electronic issue causing this. Pushing the off button didn't change the state just put it to blinking but unable to disable. Thinking it may actually be locked I pulled over and jacked up one rear tire which spun freely leading me to believe the locker was actually unlocked so I pulled the locker plug from the rear diff which dumped a bunch of water out. In doing research I found this to be an issue others have encountered and Jeep seems to be replacing the entire rear end to resolve. Unfortunately I am running 4.88 gears so Jeep wont warranty the issue. To make things worse when I picked my Jeep up from the dealer yesterday thinking it was at least drivable and unlocked the locker seems to be locked and unable to unlock. So now I am stuck locked at the dealer unable to drive my vehicle home and they are refusing to work on it due to my aftermarket re-gear (which BTW was done 2 years and over 20k miles ago). Any suggestions? Running the bypass cable I have seen from Z Automotive that other threads recommend seems like it just sends a signal back to the Jeep to ignore the bad sensor. My fear is that would potentially allow the locker to remain engaged but the Jeep doesnt know. Am I misunderstanding the bypass?

I have 38K miles on my JTR. My rear end locker light started coming on randomly around 6K miles ago. I quickly bought the Z-Automotive cable and installed in the rear. That fixed my issue. My rear lock works perfect now. I'm not sure if it will help you, but, it fixed my issue.

Note: Also, you should change your rear end fluid. It is the metal powder in the oil that makes the sensor act funny. The cleaner the gear oil, the less chance you have of issues..

 

[Phljeeper]

I have 38K miles on my JTR. My rear end locker light started coming on randomly around 6K miles ago. I quickly bought the Z-Automotive cable and installed in the rear. That fixed my issue. My rear lock works perfect now. I'm not sure if it will help you, but, it fixed my issue.

Note: Also, you should change your rear end fluid. It is the metal powder in the oil that makes the sensor act funny. The cleaner the gear oil, the less chance you have of issues..

Thank you for the feedback. I will credit the dealer, they just called and are looking at my Jeep again to see if they can fix it. Good to know they are trying. But seems like I may be in a gray area with the gearing and the proximity of the sensor. Any idea if the sensor is located inside the rear diff housing or if its somewhere else on the Jeep? That is where the issue lies, they wont warranty anything inside the diff housing.

 

[hjdca]

Thank you for the feedback. I will credit the dealer, they just called and are looking at my Jeep again to see if they can fix it. Good to know they are trying. But seems like I may be in a gray area with the gearing and the proximity of the sensor. Any idea if the sensor is located inside the rear diff housing or if its somewhere else on the Jeep? That is where the issue lies, they wont warranty anything inside the diff housing.

The sensor is inside the top of the diff housing. Evidently, it gets wet with gear oil and the metal powder causes it to malfunction...
Personally, I would try the Z-automotive cable before I spend money with the dealer on this.

 

[hjdca]

Let us know if you can just buy the sensor now... As of a year or so or longer, the sensor was not available as a separate part..., they would just change out everything. They may have fixed the availability of the sensor now...

 

[Phljeeper]

Let us know if you can just buy the sensor now... As of a year or so or longer, the sensor was not available as a separate part..., they would just change out everything. They may have fixed the availability of the sensor now...

Will do and that is what the dealer is currently investigating. Seems like that is the right fix and the replacement of the entire rear seems like a ridiculous requirement.

 

[rharr]

it is highly likely the locker sensor is caked with metal fillings and reporting a false reading. The sensor uses a magnet which attracts metal from the gears mating (one reason to change you axle oil every now and then). The fix is to clean the sensor of the metal filings. Unfortunately you need to pull the locker/carrier assembly from the axel to gain good access to it. I can't recall but you may also need to pull the ring gear too.

Dealers do a axle swap because it takes to much time for a tech to fiddle with tearing everything apart and may or may not have the skill set to do the job in the first place.

Nothing hard about the job, just time and labor. It can can be a driveway DIY job for someone ambitious. But since you already have a relationship with a axle shop that did the regear, i would have them pull it apart and inspect the sensor and clean it.

The z-cable is a bandaid fix.

I would also avoid taking the highway if the rear is indeed locked. I would find a way to take surface streets even it it took more time; being that the east coast is nothing but surface streets first, highways second not that big of a deal.

 

[j.o.y.ride]

Are you sure it's actually locked and not just the Eaton freak out flashy light?

Jack it up, turn one back wheel, does the other wheel turn the same way? If not then it's just the Eaton error and you are right, Jeep will not warranty it.

 

[Phljeeper]

Are you sure it's actually locked and not just the Eaton freak out flashy light?

Jack it up, turn one back wheel, does the other wheel turn the same way? If not then it's just the Eaton error and you are right, Jeep will not warranty it.

It is for sure locked now and we have been unable to unlock it with the on off buttons. The dealer is trying to get it to unlock and pull the plug so I can drive it home.

 

[RCKLNDR]

It is for sure locked now and we have been unable to unlock it with the on off buttons. The dealer is trying to get it to unlock and pull the plug so I can drive it home.

Not sure if the lay of the land changed in the new axles but I had the front locker fail to disengage in my JKHR which was no bueno. I ended up having to jack the front end up, pull the fill plug, shine a flashlight in, and manually disengage the locker.

 

[Phljeeper]

I wanted to provide an update. The dealer was able to get the sensor part and replaced it and the issue is resolved. They did not need to replace the entire rear or use the bypass plug. Lockers are working again and I got the Jeep back yesterday.

 

[Phljeeper]

Let us know if you can just buy the sensor now... As of a year or so or longer, the sensor was not available as a separate part..., they would just change out everything. They may have fixed the availability of the sensor now...

Yes the sensor is now available and replacing it resolved the issue.

 

[Jaxmax]

Good news on the sensor, mine failed about a year and a half ago, and I could not see it being smart to swap the whole axle, and the Z part has worked excellent and not even sure I will fix it actually, rear locks, all dash lights show it in locked or unlocked postion, there is just no sensor to confirm it is locked other then the seat of my pants.......Jack

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