Keep Those Trannys Rolling - August - 2016

Raptor’s Hill Descent Control System

In this issue, we’re going to look at Ford’s Hill Descent Control system, found on the new 2017 Ford F150 SVT Raptor. Ford has been using Hill Descent Control or HDC on the F150 Raptor, SVT, FX4, XLT, Lariat, and King Ranch models since year model 2013, but most of us aren’t aware of how the system operates.


Hill Descent Control or HDC was originally designed by Bosch (in conjunction with Land Rover) in 1993, for use on the Land Rover Freelander. At the time, the system was leading edge technology that allowed Freelander to set itself apart from all other four wheel drive vehicles.

The system allows the driver to control downhill descents in rough terrain, without touching the brake or accelerator pedal, allowing the driver to concentrate on steering the vehicle through the rough terrain. Now let’s see how the HDC system works.


The HDC system has operating parameters that limit its operation to between 2 and 12 MPH. From 13 to 20 MPH the system will remain active, but descent speeds can’t be set or maintained until the vehicle drops below 12 MPH.

When engaged, the HDC system will control the downhill descent speed by using the Powertrain Control Module (PCM), Antilock Brake System (ABS), and Cruise Control. The HDC system can be controlled from the cruise control buttons to set vehicle descent speed. If the vehicle starts to accelerate downhill without the driver’s input, the ABS will apply the brakes to slow the vehicle.

If the vehicle is going down the hill too slowly, the cruise control system will increase vehicle speed to maintain a steady speed as requested by the driver. The driver can override the HDC system by applying pressure to the accelerator or brake pedal as needed.

CAUTION — Hill Descent Control systems can’t control vehicle descent on all surface conditions, such as ice, wet, or extremely steep grades. HDC is a driver’s assist system; not a substitute for good driver judgment.


Ford’s HDC system is very easy to operate. When the demand arises: Press and release the HDC button (figure 1) located on the dash.

  1. Press the accelerator pedal or cruise control “+” button to accelerate to the desired speed.
  2. Press the brake pedal or cruise control “–” button to decrease speed to the desired speed.

Once you’ve reached the desired speed:

  1. Tap the brake pedal to engage HDC.
  2. Release brake and accelerator pedals.

…and the HDC system will do the rest. Disabling or turning the HDC system off is as easy as pressing and releasing the HDC button again.The vehicle will then resume normal operation.


Adding the HDC system to Ford’s new 2017 F150 SVT Raptor wasn’t enough for Ford’s Special Vehicle Team (SVT). Since its establishment in 1993, the SVT has been responsible for designing and developing Ford’s performance vehicles.

They went all the way with the 2017 F150 SVT Raptor by installing a 6.2L Boss V8 or 3.5L ECO Boost engine; a 10-speed automatic transmission or the 6R80 6-speed transmission (depending upon application); a unique grill, an in-dash, four wheel drive monitoring system; a front, off-road camera and camera washer; an optional, 360º camera (to view the surrounding area); dual exhaust with 3.5” exhaust tips; an electronic, shift-on-the-fly transfer case; a modified ELD rear locking differential; special high performance “Fox” shocks; and a heavy duty bumper with front end, engine, transmission, and transfer case skid plates. Ford also added an intelligent, touch screen monitor to monitor vehicle operations.


The in-dash 4X4 monitoring system allows the driver to monitor the 4×4 system operation. The monitoring system is located in the center of the instrument cluster (figure 2) and displays vehicle direction (compass), vehicle angle, vehicle tilt, front wheel orientation, and 4×4 status.


Ford’s Special Vehicle Team installed a front, off-road camera in the front grill (figure 3). The camera is equipped with a camera washing system (to clean the camera lens).

To operate the front, off-road camera, you must first be in “Off-road” mode, the electronic locking differential must be activated, and vehicle speed must be under 15 MPH.

The front, off-road camera allows the driver to see obstacles in front of the vehicle and is essential when cresting a hill. The Raptor is also available with a 360º camera.


The intelligent touch screen monitor is located above the center console (figure 4) and offers touch screen capabilities. The touch screen monitoring system allows you to access all on-board amenities, including the 4×4 system.

With the addition of Hill Descent Control and the many upgrades to the Raptor line, Ford’s 2017 F150 SVT Raptor is ready to conquer any obstacle it encounters. With a better understanding of how the Hill Descent Control system operates, you should have no problem keeping those trannys rolling.