Range Rover Classic
ABS
9
DESCRIPTION AND OPERATION
DRIVING VEHICLE
WARNING: On surfaces which are soft and
deep, for example deep powdery snow,
sand or gravel, braking distance may be
greater than with non ABS braking. In these
conditions wheel lock and the build up of snow or
gravel under wheels may be an aid to shorter
stopping distance. However it is still an advantage
to maintain the stability and manoeuvrability
available with ABS control.
1. Switch on ignition, system will automatically
carry out self test function. This will be felt as a
slight movement in brake pedal and a short,
rapid series of clicks indicating that solenoid
valves have been checked.
2. Observe warning lights, check parking
brake/fluid pressure/level warning light
extinguishes after initial bulb check or when
parking brake is released, indicating that power
assistance is available. Note time taken to
pressurise system is approximately 20 seconds.
3. Start vehicle and drive away, at 7 km/h (5 mph)
the ABS warning light must be extinguished -
see Warning Lights.
4. In road conditions where surface friction is
sufficient to slow or stop the vehicle without
wheel lock, ABS does not operate.
5. In an emergency braking situation, if one or
more wheels begin to slow rapidly in relation to
vehicle speed, ABS will detect wheel locking
tendency and will regulate brake pressure to
maintain wheel rotation.
6. ABS operation will be felt as a vibration through
pedal, at same time solenoid cycling will be
heard.
NOTE: Constant pressure on foot pedal
whilst ABS is operating is more effective
than cadence braking. Do not pump brake
pedal, this may reduce ABS efficiency and
increase stopping distance.
7. Downward travel of pedal will also feel hard at
point at which ABS operates. Little further pedal
travel is possible at this point, BUT, force on the
pedal can be varied to influence braking force
while ABS retains control.
BRAKE APPLICATION WITH PARTIAL FAILURE
WARNING: If a fault develops in brake
system it is essential that fault is
investigated immediately.
NOTE: If, during braking, a drastically
reduced resistance is detected at pedal
and braking effectiveness is very much
reduced, failure of the non-powered (master
cylinder) portion of system is indicated. When this
occurs DO NOT PUMP BRAKE PEDAL. Push the
pedal through free movement to obtain braking
effort. It is essential that brake pedal travel is not
obstructed by items such as extra footwell mats.
1. When power assistance is not available, ABS
braking is not operative. Both warning lights are
illuminated. Braking effort is available from
master cylinder only. This results in longer pedal
travel and greater pedal effort required to
decelerate vehicle.
WARNING: Foot pressure on pedal, using
master cylinder only, will not achieve
same degree of braking as is available
from power assistance.
2. If master cylinder fails, i.e. there is insufficient
fluid in master cylinder to create pressure,
braking to all four wheels is retained and ABS
remains operative. The red warning light will be
illuminated if cause of master cylinder failure is a
fluid leak and level in master cylinder is low
enough to actuate fluid level switch.