Range Rover Classic. Manual — part 131
ABS
3
FAULT DIAGNOSIS
ABS FAULT AND REMEDY CHART
SYMPTOM
POSSIBLE CAUSE
CHECK
REMEDY
ABS warning light on
ABS electrical fault
Check ABS electrical
circuit to identify fault
Change component if
necessary
High sensor air gaps
Push in sensors
Both warning lights ON.
Pedal travel and pedal
force increased
No booster pressure (fluid
loss)
Check reservoir fluid level
and inspect system for
leaks
Rectify as necessary and
refill reservoir
No booster pressure
(pump not operating)
Check electrical supply to
pump
Rectify electrical supply if
necessary
Pump faulty
Change hydraulic pump
Both warning lights ON
(no additional symptoms)
Malfunction of pressure
switch
Disconnect pressure
switch
a) If light remains
illuminated vehicle wiring
faulty
a) Test wiring, change
harness if necessary
b) If lights extinguish
pump defective
b) Change pump
Brake fluid warning light
ON
Fluid loss
Check reservoir fluid level
and inspect system for
leaks
Rectify leakage, refill
reservoir
Reservoir fluid level
switch malfunction
Check fluid level switch
Change reservoir
cap/switch
Pressure switch
malfunction
Check switch with
pressure gauge
a) If wiring faulty
a) Replace harness
b) If switch faulty
b) Change hydraulic
pump
Brake fluid warning light
ON. Pedal travel
increased, foot pressure
normal
Fluid loss from hydrostatic
circuit
Check reservoir level and
inspect system for leaks
Rectify leakage and refill
reservoir
Rebleed as necessary
70
BRAKES
4
FAULT DIAGNOSIS
SYMPTOM
POSSIBLE CAUSE
CHECK
REMEDY
Brake fluid warning light
OFF. Pedal travel
increased, foot pressure
normal
Insufficient bleeding
Rebleed master cylinder
circuit
Master cylinder
malfunction
Change booster and
bleed system
Hydraulic pump runs
constantly
Fluid loss
Check reservoir level and
inspect system for leaks
Rectify leakage as
necessary, refill reservoir
Pump non-return valve
faulty
Change hydraulic pump
Hydraulic pump runs
constantly with warning
lights OFF. Pedal travel
normal.
Malfunction of pressure
switch
Disconnect pressure
switch
Relay switch malfunction
a) If pump stops
a) Change hydraulic
pump
b) If pump continues
running
b) Change relay or cable
Pedal can be moved
downwards under
constant pressure
Seal leaking in master
cylinder
Inspect system for leaks
Change booster unit
Seal leaking in servo unit
Change booster unit
ABS
1
REPAIR
GENERAL SERVICE INFORMATION
NOTE: ABS components ARE NOT
serviceable. Replace components found to
be faulty.
Brake fluid precautions
WARNING: Do not allow brake fluid to
come into contact with eyes or skin.
CAUTION: Brake fluid can damage
paintwork, if spilled wash off immediately
with plenty of clean water.
CAUTION: Use only correct brake fluid. If
an assembly fluid is required use ONLY
brake fluid. Do NOT use mineral oil, i.e.
engine oil etc.
FLUID LEVEL CHECK / TOP UP
1. Park vehicle on level ground.
2. Turn ignition ON, to activate hydraulic pump. If
pump does not activate depress brake pedal
several times until pump operates.
3. When pump stops, check level is between ’MIN’
and ’MAX’ marks.
4. If level is below ’MIN’ mark top up fluid level to
’MAX’ mark on reservoir, using correct fluid.
See
LUBRICANTS, FLUIDS AND CAPACITIES,
Information, Recommended Lubricants and
Fluids
WARNING: Clean reservoir body and filler
cap before removing cap. Use only fluid
from a sealed container.
DO NOT OVER FILL RESERVOIR
DEPRESSURISE SYSTEM
WARNING: Before bleeding the system or
working on any component in the brake
system the following procedure MUST be
carried out to depressurise the accumulator.
1. Switch off ignition.
2. Operate the brake pedal 30 times. Pedal travel
will increase slightly and reduced resistance will
be felt as pressure decreases.
3. Wait for 60 seconds, press the brake pedal four
more times. This procedure will ensure that all
pressure is evacuated from the system.
70
BRAKES
2
REPAIR
BRAKE SYSTEM BLEED (ABS)
Service repair no - 70.25.02
Equipment: Bleed tube and a clean bottle
containing a small amount of clean liquid.
CAUTION: Clean all bleed screws, filler
cap and connections thoroughly using
clean brake fluid only. DO NOT USE
MINERAL OIL I.E. ENGINE OIL ETC.
MAINTAIN CLEANLINESS THROUGHOUT.
NOTE: Do not allow reservoir fluid level to
fall below ’MIN’ level during bleeding.
Regularly check level and keep topped up
to ’MAX’ level.
WARNING: Do not use previously used
brake fluid. Ensure only new fluid is used,
taken from a clean sealed container.
Carefully dispose of unwanted fluid in a sealed
container, marked USED BRAKE FLUID.
1. Switch off ignition and depressurise system.
Ensure ignition remains OFF until instruction 7.
2. Fill fluid reservoir with specified fluid to ’MAX’
level.
NOTE: Time consumed in filling booster
may be reduced by fitting a rubber bellows
unit to filler neck, using hand pressure to
pressurise the reservoir. A spare bellows unit
from booster push rod is suitable for this purpose.
Ensure bellows unit is perfectly clean to avoid
foreign matter entering system. Raising rear of
vehicle will assist fill procedure.
3. Depress brake pedal slowly and progressively
five times, using full pedal stroke. Release pedal
for five to ten seconds, air bubbles will rise into
reservoir.
4. Repeat instruction 3. until some resistance is
felt. If no resistance is felt check clevis pin is
connected to correct (UPPER) hole in brake
pedal
5. Bleed four front caliper lower (hydrostatic) bleed
screws in the conventional manner.
In the order: outer bleed screw driver’s side,
opposite caliper outer bleed screw, inner bleed
screw, inner bleed screw driver’s side. Depress
brake pedal slowly and progressively, locking
bleed screw at bottom of each stroke.
6. Bleed hydraulic pump - open bleed screw on
pump and allow fluid to flow until clear of air
bubbles. Do not use bleed bottle, use a clean
absorbant cloth to prevent fluid spillage.
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