I noticed that Nissan's new 4x4 models have a feature called "Hill Descent Control". Does anyone know how it works? I assume it's some kind of computer-controlled application of the brakes, but does it work only on hills or can it be used for rock-crawling as well?

For example, since the factory low range is 2.02:1, on AT's it's often necessary to apply both the gas and the parking brake to smoothly roll over obstacles and keep vehicle speed very low. Can HDC be similarly applied?

I would surmise that Nissan's version of HDC is nothing more than a spinoff of the Land Rover's system. When the vehicle exceeds a predetermined angle going down a hill the system can be engaged. The system will then use the ABS sensors to determine wheel speed and apply the brakes to keep the vehicle under control. The system will have a speed set in a control unit to keep the vehicle at about 5mph and no more than 10mph. All this can be yours with a manual transmission and some low range gears!!! Remember though that this is a computer system that is controlled by a 10cent fuse. There is not substitue for mechanical off roading helpers and computers only led to more problems and expensive repair bills!!!.

Tim

Yeah, it's just an extention of the ABS system that controls your speed when in 4Lo.
The opposite is also included in the form of the 4-wheel active limited-slip functionality, which could be useful on the rocks and such. The ABS system slows or stops a spinning wheel.

Me, I'd rather handle it all myself than have a computer calling the shots. Fortunately that stuff can be turned off.

Brent

I'd deffinetly have to agree with Brent on this one...

I've seen you drive Brent, you need more computers than anyone offers.

I've seen a lot of people drive (goneMOAB, GOX), and most of them could use the help of a computer, not just Brent.

Ian made a funny.

Yet you willingly bought an automatic Xterra

Wouldn't a HDC using the ABS eventually overload/heat the ABS? Wouldn't it stop working properly until cooled if used in excess?

Lets face the facts here. Your not going to need the system for that long. If you do then you probably shouldnt be there anyway. As far as the computer stuff goes I totally disagree. We take our M998's (H1's to civilians) places that only nuts would drive and all that mechanical goodness is great. Ive jerry rigged stuff on trucks that would make your head spin and it got us back to the motor pool. You cant jerry rig a computer!!!

Tim

Nope. What about normal driving ?

From what I heard on my secret Frontier test drive, it works quite well.

I know first hand that prolonged extreme driving and braking will overheat the ABS and it will shut down until it cools. Once that happens, it's like there is no more ABS.

I really don't expect that to happen driving down a hill.

I've seen the "active limited-slip" type stuff fail miserably in one situation. A late-model Discovery had just crossed a stream and was faced with a pretty dicey climb out on the other side. With the brakes wet (and re-wet) as he tried to climb out, they were pretty useless as far as the limited-slip functionality.

I came across a series II on Hacket Gulch Road and he said that his system had failed on him once before. The dealer said that the ABS had over heated and therefore the HDC was useless. No permanent damage just a loss of faith in the equipment. Mechanical is the only way to go!!!

Tim

Well we watched a series II try to climb Potato Salad Hill at EJS last year, and he worked it until the center diff caught on fire. The crowd loved it, his wife probably not so much.

The Disco is a good vehicle if you can find a reliable one and they are few and far between. However, I wouldnt mind having a Defender!!! Rumor has it a new one is on its way!!!

Tim