DSC switch
The DSC switch allows you to switch off the DSC function. Although Land Rover recommends that DSC be switched on for all normal driving conditions, it may be useful to switch off DSC in the following conditions to improve traction:
- The car needs to be "rocked" to free it from loose or soft soil.
- When driving on loose surfaces or with anti-skid chains.
- When driving in deep sand, snow or mud.
- When driving on a deep longitudinal rut.
The DSC switch is not a locking switch. It is mounted on the central switch panel of the instrument panel. When the DSC switch is pressed, ignition voltage is supplied to the ABS module. (anti-lock braking system). When the DSC switch is pressed for the first time, the ABS module (anti-lock braking system) turns off the DSC functions. When the DSC switch is pressed again, the ABS module (anti-lock braking system) re-enables the DSC functions. In order for the ABS module (anti-lock braking system) responded to pressing the DSC switch, the switch must be held down for at least 0.3 s. The DSC function is activated automatically at the beginning of each ignition cycle.
The DSC switch status is indicated by the DSC indicator lamp. The DSC indicator lamp does not light when the DSC function is on and lights continuously when the DSC function is off.
A request from the DSC switch to switch off DSC is ignored if there is a fault with the air suspension system or if the suspension height is set to off-road mode at a speed above 60 km/h.
To protect against incorrect operation or switch failure, the ABS module (anti-lock braking system) stores a fault code if the signal from the DSC switch is high for more than one minute.
Even when the DSC function is turned off, vehicle maneuvers involving excessive yaw or lateral acceleration may cause the function to be activated to maintain vehicle stability.
HDC switch
The HDC switch controls the activation of the HDC function.
The HDC switch is a non-latching switch mounted on the center console behind the gearshift lever. When the HDC switch is pressed and released, ignition voltage is briefly applied to the ABS module. (anti-lock braking system). When the HDC switch is first pressed and released, the ABS module (anti-lock braking system) turns on the HDC function. When the switch is subsequently pressed and released, the ABS module (anti-lock braking system) turns off the HDC function.
To protect against misoperation or switch malfunction, the function status does not change if the switch is pressed for more than 10 seconds. If the HDC switch input signal is high for more than one minute, the ABS module (anti-lock braking system) the malfunction persists.
HDC Relay
The HDC relay is used to turn on the brake lights when the brakes are applied by the HDC function and also when the parking brake is dynamically applied.
The HDC relay is a maintenance-free solid state relay mounted on the CJB printed circuit board (switching unit)The operation of the HDC relay is controlled by the ABS module. (anti-lock braking system), closing its winding to ground. ABS module (anti-lock braking system) monitors the hydraulic pressure of the brake system and activates the HDC relay during active braking. A pressure threshold and a time filter are used to prevent the brake lights from flashing during braking.
Brake light switch
The brake light switch is mounted on the brake pedal bracket and is activated by the brake pedal. The brake light switch is a two-pole switch: the brake switch (BS) pole supplies the brake pedal status signal to the ABS module (anti-lock braking system); the brake light switch (BLS) pole turns on the brake lights and also transmits a brake pedal status signal to the ABS module (anti-lock braking system) and in ECM (engine control module).
When releasing the brake pedal:
- The BS contacts close and provide ignition voltage from the CJB (switching unit) in the ABS module (anti-lock braking system).
- BLS contacts are open.
When pressing the brake pedal:
- BS contacts are open.
- The BLS contacts close and provide ignition voltage from the CJB (switching unit) for three brake lights, in the ABS module (anti-lock braking system) and in ECM (engine control module m).
ABS module (anti-lock braking system) monitors the status of the signals from the brake light switch and transmits the status of the brake pedal and the corresponding quality factor via the CAN bus (local area network of controllers).
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