12.2 FAULT DIAGNOSIS AND TESTING
rrouble
-ong brake pedal
dibration during braking
'oor braking performance
3rakes pull to one side
3rakes do not release
ixcessive pedal travel
Cause
Brake caliper piston or caliper guide
pins sticking
Worn
I damaged brake pads
Worn
1 damaged brake pads
Loose caliper mounting bolts
Insufficient grease on sliding parts
Foreign material
or scratches on
brake rotor contact surface
Damaged brake rotor contact surface
Leak
in hydraulic system
Air
in system
Worn
I damaged brake pads
Foreign material on brake pads
Brake caliper piston malfunction
Tandem master cylinder malfunction
Vacuum booster fault
Disconnected
or damaged vacuum
hose
Low brake
fluid level
Worn
I damaged brake pads
Foreign material on brake pad
Failing valves
in ABS valve block
Abnormal wear or distortion on front
brake rotor
Incorrect wheel alignment
Incorrect tire pressure
No brake pedal free play
Vacuum booster
binding
Tandem master cylinder return port faulty
Faulty valve
in ABS valve block
Leak
in hydraulic system
Air
in system
Remedy
Service or renew caliper or caliper
guide pins
Renew brake pads
Renew brake pads
Tighten caliper mounting bolts
Apply grease where necessary
Clean brake rotor contact surface
Renew brake
rotor
Repair leak. Check all pipework con-
nections. Refill and bleed the system
Check the system
for leaks and bleed
brakes
Renew brake pads
Examine brake pads and clean
or
renew as necessary
Renew faulty brake caliper piston
Service
or renew tandem master cyl- inder
Renew vacuum booster
Renew vacuum hose
Check for leaks, refill and bleed the
system
Renew brake pads
Examine brake pads and clean
or renew as necessary
Renew valve block
Examine front brake
rotor and service
or renew as necessary
Carry out wheel alignment. Refer to
Section
11, iv Service Data
Inflate tire
to correct pressure
Adjust brake pedal free play
Renew vacuum booster
Clean return
port on tandem master cy I i nder
Renew valve block
Repair leak. Check all pipework con
- nections. Refill and bleed the system
Check the system
for leaks and bleed
brakes
0
0
0
Issue 1 August 1994 16 X300 VSM
12.2 (continued)
rrouble
Excessive pedal travel (Cont'd)
Brakes grab
Brakes drag
Hard brake pedal when pressed
Excessive brake noise
Cause
Worn tandem master cylinder piston
seals or scored cylinder bore
'knock back'. Excessive brake rotor
run
-out or loose wheel bearings
Brake pads contaminated by grease
or brake fluid
Brake pads distorted, cracked or
loose
Loose caliper mounting bolts or
guide pins
Seized or incorrectly adjusted parking
brake or cable
Broken or weak parking brake return
springs
Caliper pistons seized
Brake pedal binding
at pivot points
Vacuum booster binding
Tandem master cylinder faulty
Lack of vacuum
at the vacuum
booster
Tandem master cylinder
pushrod
binding
Frozen tandem master cylinder pis
-
ton
Brake caliper piston or caliper guide
pins seized
Worn brake pads
Bent or cracked parking brake shoes
Foreign objects in brake pads or
park- ing brake shoes
Broken
/ loose parking brake hold
down springs or return springs
Loose caliper mounting bolts
Remedy
Renew tandem master cylinder
Check brake rotor run
-out and renew
as necessary. Adjust wheel bearing
Renew brake pads. Check
pipework for leaks
Renew brake pads
Check caliper and repair
/ renew as
necessary
Examine parking brake and repair
/
renew as necessary
Renew parking brake return springs
Examine calipers and repair
/ renew
as necessary
Examine brake pedal bushings and
repair
/ renew as necessary
Renew vacuum booster
Examine tandem master cylinder and
repair
/ renew as necessary
Check vacuum hose. Repair or renew
as necessary
Renew tandem master cylinder
Renew tandem master cylinder
Examine caliper and renew/ repair as
necessary
Renew brake pads
Renew parking brake shoes
Examine brake pads and and parking
brake shoes. Clean or renew as
necessary
Examine parking brake assembly.
Re- pair or renew as necessary
Re
-torque caliper mounting bolts
