![]() | Home > Technical (L322) > Hill descent control |
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rjff Member Since: 28 Oct 2017 Location: Cambridgeshire Posts: 1196 ![]() ![]() ![]() |
I think the noise you have is the system using the brakes etc. to control the car's rate of progress. It appears to pulse the brakes quickly (or not quickly), seeming like it's not at all well.
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DrRob Member Since: 16 Apr 2015 Location: Petersfield, Hampshire Posts: 4318 ![]() ![]() ![]() |
Sound is normal. Brakes doing their job |
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Rapiscan Member Since: 28 Apr 2018 Location: North Lincolnshire Posts: 182 ![]() ![]() ![]() |
Mmm? I wasn't sure if it was using brakes or a kind of telmar system as used on some buses/trucks where electromagnets are energised on the propshafts to create a "drag" to reduce speed.. OK as long as the sound we hear is the norm then, fine, thanks. 2008 L322 Vogue 3.6 TDV8 in Java Black with parchment and Navy interior. 125000mls.
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rjff Member Since: 28 Oct 2017 Location: Cambridgeshire Posts: 1196 ![]() ![]() ![]() |
We've got enough electrickery on ours without the prop brake system. Hope no one from JLR reads this or we will have more things they can engineer to go |
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Witzend Member Since: 12 Nov 2018 Location: Barnsley Posts: 17 ![]() ![]() ![]() |
Mine used to make an awful grinding sound when HDC was selected just as you describe, However, the target descent speed can be adjusted using the cruise control + or - buttons on the steering wheel. I adjusted mine relative to the gradient while HDC was in operation and was able to greatly reduce the grinding and banging noises.
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Rapiscan Member Since: 28 Apr 2018 Location: North Lincolnshire Posts: 182 ![]() ![]() ![]() |
Well ya learn something new everyday! I'll give it a go, ta! |
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appj62 Member Since: 07 Aug 2013 Location: Cheshire Posts: 424 ![]() ![]() ![]() |
Use mine when descending out of a multi-story car park in Warrington. Reassured with all the creaking and juddering, as know that the system is working correctly! Previous cars:
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kooky_guy Member Since: 25 Nov 2011 Location: Sandhurst, Berkshire Posts: 386 ![]() ![]() ![]() |
I have to say that mine is silent in operation! I'm sure its working though. 2010 4.4 TDV8 Vogue SE |
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Rapiscan Member Since: 28 Apr 2018 Location: North Lincolnshire Posts: 182 ![]() ![]() ![]() |
If its merely using the brakes, how is that better than me using the brake pedal? |
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rjff Member Since: 28 Oct 2017 Location: Cambridgeshire Posts: 1196 ![]() ![]() ![]() |
It will be calculating the variation between each wheel speed against perhaps the measured acceleration of the car and applying differing retardation to each wheel via the brakes. (I think) It will be likely more complicated than that but you get the idea. Cheers
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mjdronfield Member Since: 04 Nov 2011 Location: Derbyshire Posts: 7860 ![]() ![]() ![]() |
You can’t brake each individual wheel at varying levels to keep the car straight, using information from the sensors around the body.
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Boxbrownie Member Since: 19 May 2018 Location: FF gone now....FL2 i6 to play with Posts: 245 ![]() ![]() ![]() |
HDC is really for decent of slippery/difficult terrain decent where just using the brake pedal would result in a side slip, the HDC as above has been said uses each wheel retardation individually to balance the braking effort keeping the vehicle in a controlled decent, basically it’s not really for your multi story car park |
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Rosco Member Since: 20 Jan 2012 Location: Beyond the wall. Posts: 2587 ![]() ![]() ![]() |
get yourself on a 1:4 snow/mud covered hill and you will see the benefits, bloody noisy but does a great job ![]() |
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rjff Member Since: 28 Oct 2017 Location: Cambridgeshire Posts: 1196 ![]() ![]() ![]() |
MJ
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