Better Hill Descent Feature Understanding

[RussJeep1]

I'm not an off roader.

I have complete respect for those who choose to be: we all get to make our Wranglers into what makes us happy, within law, given the diversity of the terrain it is capable of navigating, especially when properly equipped.

That said, my understanding, and it may be totally off, is that Hill Descent, when enabled and the right conditions exist for it to activate, (4 low, operator not already applying brakes, etc.) is a method of the rig applying brakes to control speed.

This brings up two questions.

1) If this is true, that the feature is brakes only speed control, does the feature exist to let the driver better focus on things like steering when traversing off road obstacles?

2) What are the advantages and disadvantages of controlling speed off road between manual gear changes (if the use is equipped with an automatic transmission JL, then switching to manual mode) and brake application in controlling speed, especially, but not necessarily limited to when driving off road?

Thanks.

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[TA1ton]

@RussJeep1, so to answer your questions, I have to answer the second one first. The owner’s manual kinda contradicts itself in regards to the HDC. It first says it controls speed by using brakes, but then later is says that it does in fact change gears to control speed as well. The advantage is that the Jeep uses the traction control system to detect which tires have traction and actively brakes those tires when needed. Obviously using the brake pedal won’t get you the same result and you could potentially lose control. Disadvantage is that it is a computerized system and could malfunction. By that token, the brakes could malfunction also even if you were doing it the old school way. But some people don’t trust or just don’t like the system so it’s just a personal preference.

So to answer your first question, yes the system exists to allow the driver to focus on other driving tasks. It also exists to keep the driver in better control of the Jeep and to allow inexperienced drivers to enjoy some obstacles they may not otherwise be able to handle.

With all that being said, HDC is really only for off-road use because you have to be in 4-L to use it...hope this helps!

 

[shacdaddy]

I'm not an off roader.

I have complete respect for those who choose to be: we all get to make our Wranglers into what makes us happy, within law, given the diversity of the terrain it is capable of navigating, especially when properly equipped.

That said, my understanding, and it may be totally off, is that Hill Descent, when enabled and the right conditions exist for it to activate, (4 low, operator not already applying brakes, etc.) is a method of the rig applying brakes to control speed.

This brings up two questions.

1) If this is true, that the feature is brakes only speed control, does the feature exist to let the driver better focus on things like steering when traversing off road obstacles?

2) What are the advantages and disadvantages of controlling speed off road between manual gear changes (if the use is equipped with an automatic transmission JL, then switching to manual mode) and brake application in controlling speed, especially, but not necessarily limited to when driving off road?

Thanks.

I'm not 100% sure on how the HDC on my Denali works, but the times I've used it it "feels" like it's not the brakes, and maybe not even the gear. It sounds odd and I'm sure I'm wrong, but it feels "different"

 

[shacdaddy]

I'm not 100% sure on how the HDC on my Denali works, but the times I've used it it "feels" like it's not the brakes, and maybe not even the gear. It sounds odd and I'm sure I'm wrong, but it feels "different"

I should've googled before posting...yeah I'm totally wrong. Brakes. :cwl:

 

[RussJeep1]

@RussJeep1, so to answer your questions, I have to answer the second one first. The owner’s manual kinda contradicts itself in regards to the HDC. It first says it controls speed by using brakes, but then later is says that it does in fact change gears to control speed as well. The advantage is that the Jeep uses the traction control system to detect which tires have traction and actively brakes those tires when needed. Obviously using the brake pedal won’t get you the same result and you could potentially lose control. Disadvantage is that it is a computerized system and could malfunction. By that token, the brakes could malfunction also even if you were doing it the old school way. But some people don’t trust or just don’t like the system so it’s just a personal preference.

So to answer your first question, yes the system exists to allow the driver to focus on other driving tasks. It also exists to keep the driver in better control of the Jeep and to allow inexperienced drivers to enjoy some obstacles they may not otherwise be able to handle.

With all that being said, HDC is really only for off-road use because you have to be in 4-L to use it...hope this helps!

Thanks for the reply Travis @TA1ton. It got me thinking about cruise control on the JL. If you know, is that system also one that will slow down a rig set for a cruise control speed that's less than some descending hill might allow the JL to naturally achieve, by using BOTH downshifting and brakes, and if so, for both automatic and manual transmissions?

I might guess manual transmission rigs don't have their cruise control overriding their gear (read: 1st gear, 3rd gear, NOT "lifted rig with huge tires" gear) nor might automatics switched to manual gear changing.

 

[TA1ton]

No problem @RussJeep1! I’m not completely sure about the brakes and cruise control...I’m going to say that cruise won’t apply the brakes because the owner’s manual makes no mention of it and says that the system can actually be dangerous where it can’t hold a constant speed.

In an auto it will use the engine and transmission to control speed unless you have it in the “AutoStick” function. If this is the case, it operates like a manual unless leaving it in whatever gear you have selected will either lug or overspeed the engine. In a manual, it just uses the engine and leaves it up to you whether or not you want to change gears. So yeah...I’m those cases, cruise doesn't override gears.

 

[Joe98]

Can Hill Descent Control be used when not going downhill?

One reviewer likened Hill Descent Control to "Cruise Control for off-road".

So, If I am off road and I follow the Jeep's manual correctly, can I use Hill Descent Control on a rough track that is horizontal?

.

 

[TA1ton]

@Joe98; the HDC is kind of like cruise control for off-road, but it doesn’t accelerate the vehicle...only slows it down. So you won’t be able to use it on a horizontal track. If you have it engaged on flat ground the vehicle may move, but that’s like taking your foot off the brake at stop light and rolling forward. Essentially HDC just keeps the vehicle from rolling to fast. Hope this answers your question!

 

[ExitLeft]

I've actually been wondering this myself. I've always had manuals offroad. Just put in 1st or 2nd gear and crawl down the hill. I've seen guys with autos in front of me and all I see are their brake lights all the way down. I'm thinking why aren't they using the Hill Descent feature? Now, my left knee isn't what it used to be and I truly think my current JK is trying to kill me one joint at a time starting with my knee, thus I'm trading it in on a 2019 JLUR with an automatic trans. I'll be eager to see how this HDC works in person.

 

[jhonn236_AZ]

@Joe98; the HDC is kind of like cruise control for off-road, but it doesn’t accelerate the vehicle...only slows it down. So you won’t be able to use it on a horizontal track. If you have it engaged on flat ground the vehicle may move, but that’s like taking your foot off the brake at stop light and rolling forward. Essentially HDC just keeps the vehicle from rolling to fast. Hope this answers your question!

I think HDC requires help from gravity - and thus the name hill DESCENT control. You need to be on an incline and going down for the HDC to fully function. As an example: If you're going up a hill, and remove your foot from brake/gas, more than likely the jeep won't move forward and HDC won't even kick in.

I've used cruise control in a downhill and I do not think brakes were applied, though the Jeep did shifted down a gear or two to apply some engine breaking

 

[TA1ton]

@johnn236_AZ; yes...you are correct...an incline is required for HDC to work. I guess I could’ve worded my response a bit better...I apologize for that and hope there was no confusion. So to clarify my previous explanation, HDC keeps the Jeep from rolling downhill too fast but once you get to the bottom, the HDC will not maintain the set speed.

 

[KSwilly]

This is more than just brake control - you set a speed, take feet off the pedals, and let the system decide. More than once, I've used this, and heard the engine rev a bit to get over a bump. Only works at really slow speeds - 1.8 to 6MPH, so I doubt there's any shifting happening in the transmission. But it's not just brakes - it's brakes and throttle, keeping you at a target speed (which appears on the dash.)

 

[Arterius2]

Hill Descent overheated my rotors last time I used it to descend a long hill. To the point of me losing all stopping power and the vehicle was just rolling without any means to slow down. I wouldn’t recommend it for long descends.

 

[JimLee]

Hill Descent overheated my rotors last time I used it to descend a long hill. To the point of me losing all stopping power and the vehicle was just rolling without any means to slow down. I wouldn’t recommend it for long descends.

This doesn't make sense to me. I live and wheel in the desert very close to Death Valley, I use Hill Descent often coming down off of steep shelf roads and mining trails, it has never overheated my brakes. In fact the only time I have overheated my brakes was coming down a long steep hill (several miles) without using Hill Descent control. The only problem I have with the 8 speed auto transmission is that even in manual mode it will engine brake for awhile and then suddenly let go, your speed will increase suddenly, it will catch again eventually but those unwanted bursts of speed cab be dangerous on a rocky steep downhill (sorry, a little off topic there). Not saying you are wrong, but I have not experienced the same thing with hill descent control.

 

[Arterius2]

This doesn't make sense to me. I live and wheel in the desert very close to Death Valley, I use Hill Descent often coming down off of steep shelf roads and mining trails, it has never overheated my brakes. In fact the only time I have overheated my brakes was coming down a long steep hill (several miles) without using Hill Descent control. The only problem I have with the 8 speed auto transmission is that even in manual mode it will engine brake for awhile and then suddenly let go, your speed will increase suddenly, it will catch again eventually but those unwanted bursts of speed cab be dangerous on a rocky steep downhill (sorry, a little off topic there). Not saying you are wrong, but I have not experienced the same thing with hill descent control.

How long was your descent might I ask?
I was coming out of out an hour long descent.

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