What Does The HDC Do In Land Rovers?

What Does The HDC Do In Land Rovers?

Land Rovers feature the HDC, which stands for Hill Descent Control system. A driver-assistance system, the HDC allows for controlled hill descent in rough terrain without the driver having to do any braking. When the HDC is turned on, the vehicle will use the anti-lock braking system during descent to control the speed of each wheel on the vehicle. The driver can use cruise control to adjust the speed to a level that is comfortable. If the driver applies the brake pedal, the HDC system will be overridden.

The HDC was originally developed by Land Rover for use in the Freelander because it doesn’t have the lower range gears that are usually provided for four-wheel drive vehicles. When the HDC was first introduced, some people complained that the set speed was too fast for a controlled descent in conditions that were difficult or challenging. However, the technology used in the HDC was state of the art, and with the traction control system allowed the Freelander to stand out in its division in the 1990s. Later, the HDC was implemented in the Range Rover and Discovery where it was combined with low-range gears and traction control, so it could have the set speed reduced for extra control.

How Does Hill Descent Control Work?
HDC allows you to safely and smoothly descend hills when in rough terrain without having to apply the brake pedal. You can turn HDC on if you are traveling at 50 miles per hour or less, but it will only work when going 31 miles per hour or less. You can use HDC when the vehicle is in drive, reverse, or any gear. When you engage the gearbox in drive, the vehicle will automatically select the gear that is most appropriate.

After you have set the HDC, the target speed will be shown by a green marker on the speedometer. When HDC is turned off while in operation, the light will flash, and the system will fade out until the vehicle speed slowly increases. If HDC has been turned on and the vehicle is traveling faster than 31 miles per hour, then HDC will be suspended. There will be a message appear in the message center and the HDC light will flash. If the vehicle goes faster than 50 miles per hour, HDC will disengage and the HDC light will go off.

Other HDC Details
If the brake pedal is applied while HDC is turned on, the driver might feel a pulsation through the brake pedal. HDC will resume after the brake pedal is released. If the vehicle was operating with HDC on and then the motor is turned off, HDC will automatically turn off after the ignition has been turned off more than 6 hours. Each gear has a predetermined maximum speed while HDC is in operation. Vehicle speed will only increase when the vehicle is on a slope that is steep enough to increase vehicle momentum. There is a predetermined minimum speed for each gear as well. If there is a problem detected in the HDC system, the message center will indicate HDC Fault System Not Available and the HDC assistance will gradually fade out.

HDC Problems
If your vehicle’s HDC system is not functioning properly, you should have it inspected by a qualified Land Rover automotive technician. You shouldn’t attempt a steep descent if the HDC is not working or if it is displaying a warning message. Sometimes the problem could be a simple fix, but it could be something more problematic that requires a more in-depth fix. The mechanic will be able to troubleshoot the problem and determine the proper fix. With a scan device, the technician will get codes that give him or her an idea of the problem and can troubleshoot from the information that is provided.

When it comes to European automotive repair in Lehigh County, call on Schearer’s Sales and Service, Inc. Located tp conveniently serve Allentown, Bethlehem, and Macungie, PA, we have years of experience and extensive training in taking care of European vehicles, including Land Rovers. Contact us today to schedule maintenance or to have a mechanical issue addressed by one of our skilled technicians.

* Land Rover Defender on Rough Road image credit goes to: Maltaguy1.

* Land Rover Discovery 4 image credit goes to: teddyleung.