Hill Decent Control - addressing the bagging

[ozscott]

Hi all. There was an article a couple of years ago that I turned up that bags the hell out of the D2 HDC. Essentially the article says that when turned on the vehicle lurches down the hill rapidly gaining speed and then at 18kph suddenly the ABS bangs like crazy and it slows the whole rig down quickly. He is an owner. What he was saying is that the engine braking and gearing was good though so why use what he thought was such a rubbish system with it...it really was a bashing of the whole HDC set up on the D2.

Now I have used HDC since I bought my D2 new in 2002 - both without CDL and when I had the new output housing and CDL fitted much later. I have always found it a clever and useful ADDITION not substitute for proper driving and the very good gearing and engine braking on the V8 manual down hill.

When I read the article it had been a while since I had used HDC so I stuck it on a steep gradient, activated HDC, let the clutch out and down the hill I went - tried it in 1st, second, third and (silly yes) and found that the HDC (as I recalled that it did..so I was not going mad) came on immediately and applied the brakes literally at walking speed and it was all very controlled - that with 31 inch tyres.

Wondering if there is a difference in systems in manual and auto, TD5 v V8 (his was a TD5) and whether it may have differed in the later D2 years (his was a 99 from memory).

Cheers

[discowhite]

the only 2 D2's ive been in and have had the HDC on were my D2a auto td5 and redbacks D2 manual td5, the early D2 one was way quicker compaired to my D2a's system, mine was actually too slow.
but it of no concern to me now as the D4's HDC is brilliant and you can change the speed faster or slower with the cruise buttons on the steering wheel;)

cheers phil

[Basil135]

If it is not coming on until 18 kmh, makes me wonder if he has locked it back into 1st gear, low range.

The couple of times I have tried mine, it has worked perfectly.

I will admit, I was a little hesitant at first, but the hill wasn't overly steep, and there was plenty of room on both sides & at the bottom.

[LOVEMYRANGIE]

I still can't see the real reason for HDC....
if you can't decend a hill using the brake and your foot, you really shouldn't be in a 4wd and definitely nowhere near a hill.
The only time mine has ever and will ever be used was checking with a Nanocom for where an ABS fault was coming from down my street which is on a slope.
Too many functions today take away any skill requirements. One of note is Parking Assist now available on VW's. If you can't reverse park a car, quite honestly take public transport and hand your license in.....






Sent from my backyard TeePee using smoke signals.

[clubagreenie]

I have a 2000 and it's fine. In sluippery wet sandy clay around Nowra it never looked like sliding and that's on road tyres that really should be doing time strung around a tugboat. But the TC and HDC just kept it surging on, up and downhill. Can't wait till I get the CDL working and some tyres with thread. Annoyed the Hilux I went to pull out too.

[Redback]

I am not a big fan of HDC, I have use it, but my complaint about it is, on very long very steep rutted downhills it does tent to over run, not as much as the guy in the artical said, but it will do it, it can get very annoying, getting to 8kph then applies the brakes slowing it to almost a stop then letting go agian back to 8kph, on very long downhills it is a PITA especially if it is a badly rutted downhill.

Now having said that, since replacing the ECU from my D2, to the later ECU from the D2a, I have found that it doesn't seem as bad, and infact if you use second instead of first, it works much better.

For it to work properly the hill needs to be a gradual fairly smooth downhill, not many of those type of hills where we go.

Baz.

[It'sNotWorthComplaining!]

I still can't see the real reason for HDC....
if you can't decend a hill using the brake and your foot, you really shouldn't be in a 4wd and definitely nowhere near a hill.
The only time mine has ever and will ever be used was checking with a Nanocom for where an ABS fault was coming from down my street which is on a slope.
Too many functions today take away any skill requirements. One of note is Parking Assist now available on VW's. If you can't reverse park a car, quite honestly take public transport and hand your license in.....






Sent from my backyard TeePee using smoke signals.

A drunk driver parking, Sorry officer I'm only the passenger, the car was doing the driving;)

[ozscott]

I still can't see the real reason for HDC....
if you can't decend a hill using the brake and your foot, you really shouldn't be in a 4wd and definitely nowhere near a hill.
The only time mine has ever and will ever be used was checking with a Nanocom for where an ABS fault was coming from down my street which is on a slope.
Too many functions today take away any skill requirements. One of note is Parking Assist now available on VW's. If you can't reverse park a car, quite honestly take public transport and hand your license in.....






Sent from my backyard TeePee using smoke signals.

Thats one way of putting it mate - although light handbrake with a direct activation on the drive line (all 4 wheels then if the CDL is locked) is my preferred way if no HDC and I agree that low first in the manual is a sweet thing, but what none of downhill techniques that is driver involved can do is to brake each wheel so quickly and individually - so if it adds safety and comfort why not use it (I agree that you should know how to simulate ETC if it does out to lunch using 2 foot driving and know how to stall start and go down a hill 'manually' etc).

Cheers

[isuzurover]

I still can't see the real reason for HDC....


That's because you live in WA, there are no hills on the west coast :D

I am not a fan of HDC and think it is set far too fast on many vehicles to be of much use.

I have seen (and experienced) cases where a hill is so greasy that after a failed attempt at climbing that you slide down while the wheels are still turning forwards with both lockers engaged.

There are also times going down greasy hills that you need to accelerate (rather than brake) so you clear the treads and can get traction again. I am not sure that HDC would help in either of these cases.

[roverrescue]

Back in the good ol days of proper toyotas- ala 40series.
The Donovan Range north of Cape Trib was a longgggg steeeeeep steep clay slope.

After rain the clay slope resembled the fabled "frictionless surface" one reads about in physics text books. One "respected" HDC technique was to sit at the top of the drop, engage reverse, start rolling and then declutch to get the wheels spinning backwards... accelerate to slow and control steering to some extent. I think part of me would have loved to have try it but the fun police went and concreted the big slopes years ago now.

I apologise that this anecdote is completely offtopic from computer controlled whizzbangery.

S