Hill Descent Control Switch

WARNING: This page is about a different car, the 2018 Land Rover Discovery and 2017 Land Rover Discovery. However, it is still accessible from the selected car via links, so may be relevant.

The Hill Descent Control (HDC) switch controls the selection of the HDC function.

The HDC switch is a non-latching switch installed in the Terrain Response® switchpack, in the floor console. Pressing and releasing the HDC switch produces a High Speed (HS) Controller Area Network (CAN) chassis bus message from the Terrain Response® switchpack to the Anti-lock Brake System (ABS) control module. With the first press and release of the HDC switch, the ABS control module enables operation of the HDC function. When the HDC switch is pressed and released again, the ABS control module disables operation of the HDC function.

To guard against incorrect operation or a broken switch, if the switch is pressed for more than 10 seconds no change of state occurs. If the input from the HDC switch is held high for more than one minute, a Diagnostic Trouble Code (DTC) is stored in the ABS control module.