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Discussion Starter #1
I am having some confusion on my transfer case... I recently went wheelin'. When I throw my rig into 4L the light on the dash is on, but when I put it into 4H the light is not on... is this normal?
 

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Grooving With A Pict
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I am having some confusion on my transfer case... I recently went wheelin'. When I throw my rig into 4L the light on the dash is on, but when I put it into 4H the light is not on... is this normal?
What year? The instrument clusters are slightly different on the early JK's, but either way it should be illuminated if you are in 4 high or 4 lo.
 

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Which light? The "4WD" light should come on in either 4HI or 4LO. In 4LO you should also get an "ESP Off" light.
 

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Well an extra light will also come on in 4L only to tell you that ABS and ESC are off.
You can't travel at highway speeds in 4L so you don't need any of the nanny safeties.
 

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Discussion Starter #5
I have a 2016 WWJK, I used 4L for some of the more difficult obstacles/ the 4WD light was on, when I was in 4H no light was on. Im going to check again when I leave work tonight. If it does not come on I still covered by the power-train warranty and will put up with the dealership...
 

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The “4WD Indicator Light” (located in the instrument
cluster) alerts the driver that the vehicle is in four-wheel
drive, and the front and rear driveshafts are locked
together. The light will illuminate when the transfer case
is shifted into the 4H position.

From the manual
 

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Discussion Starter #7
I understand that, I referred to the manual first before hitting the forum. My confusion arose from the 4WD not coming on in 4H but in 4L. Wasnt sure if that was something I should be concerned about.

The “4WD Indicator Light” (located in the instrument
cluster) alerts the driver that the vehicle is in four-wheel
drive, and the front and rear driveshafts are locked
together. The light will illuminate when the transfer case
is shifted into the 4H position.

From the manual
 

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The light should be on in 4Hi or 4Lo, absolutely.

I've used 4Low two or three times, I use 4Hi somewhat often. Light always comes on. 2013 10A, but I think it's the same on the 2016.
 

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I understand that, I referred to the manual first before hitting the forum. My confusion arose from the 4WD not coming on in 4H but in 4L. Wasnt sure if that was something I should be concerned about.
Yeah something to have checked out. I just wanted to make sure you had some ammo before you headed to the dealer. :)
 

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Discussion Starter #10
I will update you guys later tonight once I am out of work. I am hoping it was a glitch or something... The dealership takes forever.....
 

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It's not a 4WD "hi" or "low" indicator.



It's simply a "4WD" indicator and as such it's supposed to be on in BOTH low and hi. I have a 2017 JKUR and that's the way it has always worked for me.
 

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Are there any potential issues if you are mechanically in 4H but the computer thinks you're in 2H? That of course assumes it isn't purely an issue with the light, and that the computer actually knows you're in 4H, which may be the case. And this all of course assumes you are actually in 4H, which should be obvious so probably doesn't need to be asked.

But I don't know what if any of the vehicles systems behave differently in 4H vs 2H besides having the driveshafts locked together, so would be interested to learn. Does BLD work in 2H, or maybe that only kicks in for 4WD?
 

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Are there any potential issues if you are mechanically in 4H but the computer thinks you're in 2H? That of course assumes it isn't purely an issue with the light, and that the computer actually knows you're in 4H, which may be the case. And this all of course assumes you are actually in 4H, which should be obvious so probably doesn't need to be asked.

But I don't know what if any of the vehicles systems behave differently in 4H vs 2H besides having the driveshafts locked together, so would be interested to learn. Does BLD work in 2H, or maybe that only kicks in for 4WD?

Yes it can cause issues with the front drive line if you are in 4WD on dry pavement-- which can lead to broken axles, gears, and increase tire wear. It is easy to tell if you are in four wheel drive even if the light is not working by turning the wheel full either right or left and move forward slowly on pavement or other hard surface. If the Jeep lurches (jerks) while the wheel is cut fully it is in four wheel drive. This will also give you a feeling for the forces at play when you drive on tar in 4wd.
 

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Are there any potential issues if you are mechanically in 4H but the computer thinks you're in 2H? That of course assumes it isn't purely an issue with the light, and that the computer actually knows you're in 4H, which may be the case. And this all of course assumes you are actually in 4H, which should be obvious so probably doesn't need to be asked.

But I don't know what if any of the vehicles systems behave differently in 4H vs 2H besides having the driveshafts locked together, so would be interested to learn. Does BLD work in 2H, or maybe that only kicks in for 4WD?

I'm pretty sure BLD is only active in 4wd. The normal TC is active in 2wd (unless you turn it off)


People tend to mistake the two systems and they are not the same. TC is about applying brakes to the spinning wheel UNTIL the other wheel starts spinning (losing traction), then the brake is released. This cycle occurs over and over again. TC will automatically throttle you down to minimize total wheel spin, and I'm pretty sure tc compares the speed of all four wheels to get a bearing on the amount of wheel spin which is occurring, so it knows how much to throttle down.



BLD instead only compares the wheel speed on the other side, and can be independently active on the front axle, rear axle, or both. It's is about applying brakes to the spinning wheel to the point where the wheel on the other side is matching the speed. It doesn't care how much the wheels are spinning... just so long as they are spinning at the same speed. From my experience BLD doesn't really compare front wheel speed to rear so it doesn't throttle you down like TC does.
 

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Discussion Starter #15
I was seeing if anyone experienced what I have. When putting it in 4H and going through corners/going full lock I do feel the binding/wheel hop. I wonder if it is just a glitch in the system... I dont mind as long as the 4WD does work! Also my Jeep terminology isnt the best... what is BLD???

It's not a 4WD "hi" or "low" indicator.



It's simply a "4WD" indicator and as such it's supposed to be on in BOTH low and hi. I have a 2017 JKUR and that's the way it has always worked for me.
 

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I was seeing if anyone experienced what I have. When putting it in 4H and going through corners/going full lock I do feel the binding/wheel hop. I wonder if it is just a glitch in the system... I dont mind as long as the 4WD does work! Also my Jeep terminology isnt the best... what is BLD???
Brake Lock Differential. I'll try to find the thread that explains it vs. me trying to regurgitate it. :)

edit: Here ya go https://www.wranglerforum.com/f274/brake-lock-differentials-bld-explained-803194.html
 

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I was seeing if anyone experienced what I have. When putting it in 4H and going through corners/going full lock I do feel the binding/wheel hop. I wonder if it is just a glitch in the system... I dont mind as long as the 4WD does work! Also my Jeep terminology isnt the best... what is BLD???
Binding on dry pavement is normal with part time 4WD. There is a section in the owner's manual warning against using 4WD on dry pavement. Tire wear and even damage can result. This link explains why -> part time 4WD systems can not be used on pavement

BLD is brake lock differential.

Open differentials are designed to send the power to the wheel with the least traction. So, if one wheel is in the air and the other is on a rock, the one in the air will spin since it has the least traction. As a result, you won't go anywhere.

The BLD system detects when one wheel is spinning faster than the other. It will apply the brake to the spinning wheel so that some of the power is transferred to the wheel that has the most traction.
 

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Discussion Starter #18
Oh I do not use 4WD on dry pavement, I just tested it to make sure it was functional after seeing the light not coming on in 4H. Also I know a decent amount about BLD, it just didnt click when reading "BLD" But I did learn a bit more on this thread!

Binding on dry pavement is normal with part time 4WD. There is a section in the owner's manual warning against using 4WD on dry pavement. Tire wear and even damage can result. This link explains why -> part time 4WD systems can not be used on pavement

BLD is brake lock differential.

Open differentials are designed to send the power to the wheel with the least traction. So, if one wheel is in the air and the other is on a rock, the one in the air will spin since it has the least traction. As a result, you won't go anywhere.

The BLD system detects when one wheel is spinning faster than the other. It will apply the brake to the spinning wheel so that some of the power is transferred to the wheel that has the most traction.
 

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I was seeing if anyone experienced what I have. When putting it in 4H and going through corners/going full lock I do feel the binding/wheel hop. I wonder if it is just a glitch in the system... I dont mind as long as the 4WD does work! Also my Jeep terminology isnt the best... what is BLD???

In the Wrangler and older Grand Cherokee
The axle hubs are permanently locked (u can change this to locking hubs for fuel and HP gain) and so the ENTIRE front axle, gears, pinion and front drive shaft are spinning at ANY speed, in 4X4 OR 2X4.
The only reason the front left and right tires can spin at separate speeds ( ie turning a corner) is the spider gears of the differential.
If u have a LOCKER u may have binding if the tolerances are not in spec or if excessively worn.
Also if the spider gears are binding themselves (ie varnish or wear) causing the differential to BIND during a turn.
I had this alot with my 2010 Grand Cherokee. Every year or two was pulling the cover and cleaning entire axle housing with mineral spirits.
Main reason i got rid of that truck.
 

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Also I've seen u-joints of the shaft failing or rusting up within 2 years and causing wheel hop.

As for the light, u may have a alignment issue with the indicator switch. Try putting in 4x4 hi remaning
stationary and slowly move around the 4x4 selector seeing if the indicator comes on as u are moving it from 2x4 to 4x4 hi to 4x4 low. Probably do this in Neutral.
Apply side pressure both directions
(Left forward and back , right forward and back)
 
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