4WD Low Observations

[JoeBelt]

I had an opportunity to experiment a bit. 2WD no sound. 4WD H no sound. 4WD L I get the metallic clicking sound while driving at a walking pace across a flat dirt lot which this time is also wet after raining all night. Highly unlikely to be a binding issue.

To me it sounds like ABS engaging similar to what you'd expect to hear if braking in snow/slush or using HDC. Why it would be engaging in this situation I don't know but I can't imagine what else it would be. It mostly occurs during turns and it's a Sahara so maybe BLD is thinking the outside tires are slipping? It doesn't bother me I'm more curious than anything. If BLD is engaging in these conditions it's programmed to very aggressive - a good thing.

Short video of the sound from diver's footwell:
https://photos.google.com/photo/AF1QipPRUoHJsWxbc1ymS8o4xjNjZtCfBTp_2hA7foI0

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[ChattVol]

I had an opportunity to experiment a bit. 2WD no sound. 4WD H no sound. 4WD L I get the metallic clicking sound while driving at a walking pace across a flat dirt lot which this time is also wet after raining all night. Highly unlikely to be a binding issue.

To me it sounds like ABS engaging similar to what you'd expect to hear if braking in snow/slush or using HDC. Why it would be engaging in this situation I don't know but I can't imagine what else it would be. It mostly occurs during turns and it's a Sahara so maybe BLD is thinking the outside tires are slipping? It doesn't bother me I'm more curious than anything. If BLD is engaging in these conditions it's programmed to very aggressive - a good thing.

Short video of the sound from diver's footwell:
https://photos.google.com/photo/AF1QipPRUoHJsWxbc1ymS8o4xjNjZtCfBTp_2hA7foI0

Hey...my 6 speed sport s makes the same distinct electrical clicking noise in 4wd low offroad. I've heard my ball joints click, but this sound is different and sounds like an electrical relay under the steering column. It does it frequently when offroad in 4wd low...doesnt feel like cv joints or ball joints. It seems like abs or traction control is clicking on and being overridden. Did you find out what it is? @chevymitchell Any ideas?

 

[Punkindave]

The Sahara has LSD front and rear right?? If the noise is when turning, that could be it.
Also there is driveline lash in the gears.

 

[Sean L]

The Sahara has LSD front and rear right?? If the noise is when turning, that could be it.
Also there is driveline lash in the gears.

Limited Slip Diff is only on the rear axle, if that option was bought. The front axle will still be an open diff with BLD active in 4LO.

 

[JROOO]

I had an opportunity to experiment a bit. 2WD no sound. 4WD H no sound. 4WD L I get the metallic clicking sound while driving at a walking pace across a flat dirt lot which this time is also wet after raining all night. Highly unlikely to be a binding issue.

To me it sounds like ABS engaging similar to what you'd expect to hear if braking in snow/slush or using HDC. Why it would be engaging in this situation I don't know but I can't imagine what else it would be. It mostly occurs during turns and it's a Sahara so maybe BLD is thinking the outside tires are slipping? It doesn't bother me I'm more curious than anything. If BLD is engaging in these conditions it's programmed to very aggressive - a good thing.

Short video of the sound from diver's footwell:
https://photos.google.com/photo/AF1QipPRUoHJsWxbc1ymS8o4xjNjZtCfBTp_2hA7foI0

For what it’s worth, Joe, I have the same strange noise and assumed normal operation. I spent two days last week at the Rubicon trail mostly in 4lo, so I know the noise you’re referring to well but I have no problems to report.

 

[telix]

Not to sidetrack the conversation - but you can get binding in 4 low even with the lockers off? I thought binding only happens if the front or rear lockers are engaged and 4 low would just make sure one tire in the front and one tire in the rear are moving - with the lower gear ratio

 

[COSJL]

Not to sidetrack the conversation - but you can get binding in 4 low even with the lockers off? I thought binding only happens if the front or rear lockers are engaged and 4 low would just make sure one tire in the front and one tire in the rear are moving - with the lower gear ratio

You could get binding in 4lo and 4hi. Basically when you are turning,front and rear wheels need to have different speeds. 4hi/4Lo will not allow a different speed between front and rear , hence the binding. If you are going straight or if the tires can easily slip, it is no longer an issue. Lockers make it even worse but even 4hi/4lo is part time(excpet Sahara with 4auto) and only to be used in slippery conditions.

 

[RangerRobAZ]

“Mattius1337 said: ↑
I'm getting a similar click. JL sport s, 3 weeks in ownership, at 700km. While in 4 low( so slow speeds), i get a rapid clicking in my steering column sounds almost electrical in nature, yet at the same time these videos are making me think its this. It happens when i'm turning most often, but impacts to the suspension( coming down off a rock) or a rough trail exacerbate the frequency of it happening. 4 high no noise, 2wheel no noise. It really wigs me out, what if something dies while i am in the bush? Ill be taking mine in this next weekend, as they owe me a a detail.”

This... so I’m not the only one. So it’s possible the CV joints are not tightened to spec. I’ll do some more dirt lot laps and pay closer attention.

i know this post is a little old, but were you ever able to track this problem down? I am having the exact same issue with a brand new 2020 jlur. Except I also get a grinding noise sometimes too and the clicking can happen in 4Hi as well. A local mechanic said the ABS sensors are terrible in the JLs and maybe that is related. I am going to try pulling an abs sensor connector off one of the wheels tomorrow to see if that disables ABS and then if I still hear the sound. I couldn’t find a fuse or relay labeled for ABS (brake vac pmp fuse disabled ESC, but not ABS). Disconnecting the ABS module entirely prevented the vehicle from starting. I am not near a Jeep dealer currently, otherwise I would have already gone in.

 

[jessedacri]

I've heard this in mine too. I think this is just the relays clicking on and off for the brake-actuated traction system no? Doesn't the jeep try and route power in open diff scenarios when it detects slip regardless of TCS on or off? I may be wrong about that.

Even if not I thought that it was similar to the fact that if you operate the window buttons while the doors are off, you still get the motor relay clicking on and off as if it was driving the nonexistent window motor. Maybe in this case it's the system doing its job but the feature is turned off further downstream to the actual hardware that pulls off the task.

Just speculating here.

 

[HoundDude]

^ interesting theory, hadn't thought of this. BTW, I think they call it brake lock differential (BLD).

 

[RangerRobAZ]

^ interesting theory, hadn't thought of this. BTW, I think they call it brake lock differential (BLD).

I've heard this in mine too. I think this is just the relays clicking on and off for the brake-actuated traction system no? Doesn't the jeep try and route power in open diff scenarios when it detects slip regardless of TCS on or off? I may be wrong about that.

Even if not I thought that it was similar to the fact that if you operate the window buttons while the doors are off, you still get the motor relay clicking on and off as if it was driving the nonexistent window motor. Maybe in this case it's the system doing its job but the feature is turned off further downstream to the actual hardware that pulls off the task.

Just speculating here.

yes, I believe you are correct. This has been my conclusion as well. The BLD (brake lock differential) would likely be paying a lot of attention on dirt roads and crawling over rocks.

my grinding noise I discovered is the exact same noise that happens when I slam on the brakes on a dirt road and the ABS kicks in. Sounds god awful. This may just be the way jeeps sound, though. I am not sure why I get that same grinding noise when going up a steep hill or other slipping situations, except to guess that BLD is using the same system components. I don’t know if this is normal on a wrangler, or if I have something defective from factory to make such a loud grinding noise. I am going to test again with my front lockers on to see if the noise goes away.

 

[D60]

Ok if it is BLD it ain't hard to test. Check this video to see a BLD engage (and disengage) a zillion times per second.


Basically (from what I can surmise - and I'm no EE) it's comparing left and right wheel speeds a zillion times per second. But the only way it can know if it's no longer needed is to release the brake, see if that wheel still overspeeds the other, and then lock that brake again if so.

Rinse and repeat to the Nth power x one trillion

Come to think of it, reminds me of an impact wrench.....hit, release, hit release, until required force is so low you no longer trip the clutch mechanism

I'm NOT saying "mystery solved" -- I'm saying it'd be pretty easy to support or eliminate the hypothesis by mimicking what they do in the video -- and preferably with a helper as an outside observer

 

[Sean L]

Ok if it is BLD it ain't hard to test. Check this video to see a BLD engage (and disengage) a zillion times per second.


Basically (from what I can surmise - and I'm no EE) it's comparing left and right wheel speeds a zillion times per second. But the only way it can know if it's no longer needed is to release the brake, see if that wheel still overspeeds the other, and then lock that brake again if so.

Rinse and repeat to the Nth power x one trillion

Come to think of it, reminds me of an impact wrench.....hit, release, hit release, until required force is so low you no longer trip the clutch mechanism

I'm NOT saying "mystery solved" -- I'm saying it'd be pretty easy to support or eliminate the hypothesis by mimicking what they do in the video -- and preferably with a helper as an outside observer

Here's a good video on Icloud of my frond BLD in action. You can see the front left wheel periodically stop, but some movement was allowed as I had three points of contact, and the rear limited slip differential did not come in to play.

https://www.icloud.com/sharedalbum/#B0Z59UlCqrAgDB;E9B771A4-0D41-472A-A53D-01E618952859

 

[INCRHULK]

If it's clicking...it could be your CVs (since it's a Sahara)...though why it's only happening in 4L is odd. Any chance it actually is the ABS malfunctioning? How many miles on your Jeep? Easiest solution for diagnosis....have someone else drive in 4L while you walk beside and try and see where it's coming from.

Saharas only have CVs if they have the full-time 4wd transfer case (Selec-Trac).

 

[RangerRobAZ]

Here's a good video on Icloud of my frond BLD in action. You can see the front left wheel periodically stop, but some movement was allowed as I had three points of contact, and the rear limited slip differential did not come in to play.

https://www.icloud.com/sharedalbum/#B0Z59UlCqrAgDB;E9B771A4-0D41-472A-A53D-01E618952859

So when doing that or similar off road maneuvers, do you notice any loud grinding noise? Same sound as when ABS kicks in for me.

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