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Mystery Button

3118 Views 16 Replies 7 Participants Last post by  Gilgorm
I noticed a mystery button on the lower left of the sport auto shifter. I know the last button is for the Park Distance Control, above that is the side-top view camera, but what is that one right above it. I rarely see that on any 5 series.

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Thats the HDC, hill descent control.
Yup, hill descent control. Just tried it on a 30%hill many times over a week. Indicator on dash was red and as we went over the crest, I released the brake, the car picked up speed, the indicator went green and controlled the speed perfectly all the way to the bottom. As we slow onto level ground the indicator went red again. Fun to use.
I believe that is the mother-in-law ejection button. It is rarely seen because most of us would not allow our mother-in-law to sit in the front seat of our f10 under any circumstances.
I noticed a mystery button on the lower left of the sport auto shifter. I know the last button is for the Park Distance Control, above that is the side-top view camera, but what is that one right above it. I rarely see that on any 5 series.
Oh..HDC that makes sense as it is only available with XDrive vehicles so only 550xi will have it.
Thats the HDC, hill descent control.
I have try out the HDC one of these days. The last car I had make a loud clunking noise when using the HDC, does the 5 series do the same thing?
Yup, hill descent control. Just tried it on a 30%hill many times over a week. Indicator on dash was red and as we went over the crest, I released the brake, the car picked up speed, the indicator went green and controlled the speed perfectly all the way to the bottom. As we slow onto level ground the indicator went red again. Fun to use.
Have an '11' 535xi with it and no noise. If it does make a noise get to the dealer right away! It's as silent and effective as the cruise control it's tied to. Don't use it too much here at home as there aren't that many steep hills to need it. However a few months ago at the in-laws home in Eastern KY/Western VA it was a blast and let me pay extra attention to the edges of those narrow coal roads we had to traverse. Great feature.
I don't have a HDC button (no sport package). I do notice that the car downshifts when the car exceeds the speed set in cruise control to apply some engine braking, though. Does the HDC button do something different than that?
Yes, it applies the rear brakes as needed to maintain speed. This is the answer as to why the rear brakes have a shorter expected life than the front brakes. :thumbup:
Not a sound. Other than the dash indicator changing colour there is no indication of any kind. There is a yaw control build in so it shuts off automatically on a flat surface. I've heard before its only on X-drives but can't confirm. I'm in an X-drive with no M-Sport.
I have try out the HDC one of these days. The last car I had make a loud clunking noise when using the HDC, does the 5 series do the same thing?
Oops, forgot the other half - er, major part of the reason for early rear brake wear - that being that the cruise control also applies the brakes when coasting down an incline. Since guessing most of us with X vehicles don't use the HDC that much, 10-20% +/- of the additional wear comes from use of the cruise. In any case it varies widely by user. Guten fahrt!
My MB GL sounded like it was tearing itself apart underneath while in HDC mode under extremely icy conditions. I turned it off one of time and the SUV immediately started sliding sideways. I turned back on and it regained control. The GL gave me 63k trouble free miles before trade-in, so I assumed it was supposed to be noisy.
I have try out the HDC one of these days. The last car I had make a loud clunking noise when using the HDC, does the 5 series do the same thing?
Doesnt the HDC use the brakes as well?
Oops, forgot the other half - er, major part of the reason for early rear brake wear - that being that the cruise control also applies the brakes when coasting down an incline. Since guessing most of us with X vehicles don't use the HDC that much, 10-20% +/- of the additional wear comes from use of the cruise. In any case it varies widely by user. Guten fahrt!
Xmen, counting your reply I said it twice at my responses # 5&7 above. To repeat HDC and cruise both apply the brakes as needed to maintain the set speed. Cruise for speeds 20mph and faster - up, down or on the level and HDC for 25mph and less downhill only.
I used the HDC 6 days in a row on a 30 degree hill. The 'and less' part of your comment is correct since the car was moving but nowhere near 25mph. Perhaps the hill was too steep to go any faster but the car went at about the same speed I would have gone if I had used the brakes myself. I doubt I was going 10 mph.
BTW, since the rear brakes are typically used less often, on the F10s the brake pads and rotors are made of thinner material than the front sets.
HDC for 25mph and less downhill only.
You change the speed of the HDC with the same controls as the cruise.
True enough. My car minimum speed is 10kph(6mph-walking speed which is what I used on a very steep hill) up to a max of 26kph(16mph).
You change the speed of the HDC with the same controls as the cruise.
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