HILL DESCENT CONTROL-How it works

[muneeb]

Hi Guys,
I have 2005 Lumina LTZ. When car is parked on unsmooth road, and i take gear out from P to R or D, a message "HILL DESCENT CONTROL OFF" appears in Message centre along with a car symbol.I need to know what does it means when how does this system work.

[leethal1]

Hello Muneeb,

HDC works from the ABS/BrakeAssist unit, the change from older units is that the abs unit no longer just releaves brake pressure from a locked up wheel it can also increase line pressure to apply a brake - this is how hill decent control, brake assist and some aspects of ESP work, when Hill Decent Control is activated there should be a whine coming from under the bonnet and when decending down hills you can hear the system working, sounds like normal ABS sound, you can adjust your speed with the cruise control increase and decrease speed.

I was under the impression that this is an Adventra only thing, to activate it there is a button next to the esp button. You may have some software issues with your dash to have that come up.

[Torquative]

it is an Adventra only thing. I do remember reading years ago there was a programming issue on some of the earlier dash boards that would throw it up as a fault.

Unless its an AWD Adventra station wagon, then the car definitely DOES NOT have HDC

[muneeb]

Dear Friends,
I dont think that this is a programming issue.Because when the car is parked on very smooth surface and gear is shifted from P, it does not give me any HDC message.Kindly can anyone tell me from where i can get the car's owner manual in pdf or other electronic format?


Regards,
Muneeb

[Torquative]

The Sedan and Wagon book doesnt mention HDC AT ALL, as its not an option on these cars.
Im not sure where to obtain a PDF version of it.

However, below is from the Holden Service Manual which may help.

The only HDC mentioned is for AWD Wagon.

For HDC to be activated, you need to physically turn it on and it says on the dash that its ON and will display HDC ON in the window.
If yours is only flashing that its turned OFF, that indicates its a programming fault with your dashboard. You need to turn the system on to turn it off in cars fitted with it, and to do that you need to press a button.

That sounds like a programming issue with your cluster or a module. Something is telling the dash board HDC is off when it shouldnt as HDC isnt installed.

[muneeb]

I do agree with you that HDC is only for wagons.But one thing that stucks to my mind is, why this message appears only when car is parked on unsmooth Surface?

[Torquative]

/\ that I dont know, it sounds like somethings not right with an ECU of some description which is causing it to send the message.