1213 1200.01
11
BRAKE TROUBLESHOOTING
A. Excessive travel in actuator mechanism:
Possible cause:
Corrective action:
Low fluid in master cylinder reservoir; air in
hydraulic lines.
Refill master cylinder and bleed system.
Leaking primary cup in master cylinder; ports
closed or restricted with dirt; defective hoses;
leaking check valve fails to hold hydraulic
pressure.
Check all components and make
corrections required.
Excessive lining-to-drum clearance.
Adjust brakes (drum) or replace linings.
Leaks in hydraulic lines.
Replace defective lines.
B. Pressure build-up in hydraulic system:
Possible cause:
Corrective action:
Emergency brake cable pulled.
Reset emergency brake per
manufacturer’s instructions.
Master cylinder piston fails to stop, keeping
compensating port closed.
See Authorized Dealer.
Contaminated fluid causing rubber cups to
swell.
Drain, flush and replace fluid, replace cups
and rubber hoses.
Hose cylinder ports closed or restricted with dirt,
or weak return spring.
Overhaul or replace.
Back up solenoid stuck or inoperative
Repair or replace as necessary.
C. Brake noise
Possible cause:
Corrective action:
Worn or cracked drum or rotor machined
beyond allowable oversize limits.
Replace drum or rotor.
Vibration with loose bolts, out-of-round drum or
rotor.
Tighten hub bolts, recondition or replace
drum or rotor.
Shoe/pad clatter, lining coated with grease.
Correct cause of grease leakage, reline
and grind for proper contact.
Vibration with loose bearing adjustment or
rough bearing action.
Adjust and lubricate bearings or replace.
D. Brakes lock in reverse
Possible cause:
Corrective action:
Inoperative solenoid (disc brake)
Check trailer to tow vehicle connection,
check electrical signal. Replace solenoid.
Out of adjustment (drum brake)
Adjust linings
