L322 Range Rover System Description and Operation
BRAKES
70-26
DESCRIPTION AND OPERATION
Operation
ABS Braking Mode
The ABS ECU controls the ABS function of the system in two ways:
1 Engine intervention
2 Braking intervention.
During brake intervention the ABS ECU energizes the inlet and outlet solenoid valves of the related brake and starts
the return pump. The inlet solenoid valve closes to isolate the brake from pressurized fluid; the outlet solenoid valve
opens to release pressure from the brake into the expansion chamber and the return pump circuit. The brake releases
and the wheel begins to accelerate. The ABS ECU then operates the inlet and outlet valves to control the supply of
hydraulic pressure to the brake and apply the maximum braking effort (for the available traction) without locking the
wheel.
Dynamic Stability Control (DSC)
The DSC system is designed to improve the lateral stability of the vehicle in all driving situations.
The DSC system is active unless switched off by the DSC switch in the dashboard. When switched off the DSC
warning lamp is permanently illuminated.
1 DSC switch
DSC optimises dynamic stability, even in critical driving situations. The system controls dynamic stability when
accelerating and when starting from a standstill. Additionally, it identifies unstable driving behaviour, such as under-
steering and over-steering, and helps to keep the vehicle under control by manipulating the engine output and
applying the brakes at individual wheels. Some noise may be generated when the brakes are applied. The system is
ready to operate each time the engine is started.
The indicator lamp in the instrument pack extinguishes shortly after the engine has been started (see earlier section).
If the indicator lamp flashes, the system is active, regulating engine output and brake forces. If the lamp does not
extinguish after starting the engine, or illuminates continuously during a journey, the system has a fault, or has been
de-selected using the switch provided. Without DSC, the vehicle may be driven as normal, but at the limit of adhesion
its behaviour will be less predictable.
M70 1185