5-4 F-1005-1018
TROUBLESHOOTING GUIDE
TABLE OF CONTENTS
Brakes
For maintenance procedures, see “Brake System
Maintenance” on page 4-16.
PROBLEM PROBABLE CAUSE SOLUTION
NO BRAKES OR BRAKES ARE
INTERMITTENT
Brake air system improperly connected Reconnect hand valves properly.
Relay/Emergency valve plugged Clean valve.
Defective tractor protection valve Repair or replace.
Restricted tubing or hose line Locate and eliminate restriction.
Broken line Locate break and repair.
Tractor air system failure Troubleshoot tractor air system and
repair. Check ABS system function.
SINGLE BRAKE DRAGGING OR
LOCKED
Broken internal brake component Locate and replace broken part (See
“Axle and Brake Assembly” on
page 4-20.)
Flat spot on cam roller or cam shaft Replace and lubricate.
Improper adjustment Adjust slack adjusters (See “Axle and
Brake Assembly” on
page 4-20.)
Spider bushing or cam bracket bushing
binding
Lubricate or replace bushing.
Improper lubrication Lubricate per 4-1 and 4-2
Worn brake shoe bushing Replace bushing.
Brake drum distortion Replace drum.
Broken brake chamber spring Replace spring.
Brake chamber pushrod binding Re-align brake chamber bracket.
Air brake line loose or broken Tighten or repair.
UNEVEN BRAKES See “SINGLE BRAKE DRAGGING OR LOCKED”
Restriction in hose Locate restriction and remove.
Worn brake linings Reline brakes.
Grease on linings Reline brakes.
Broken slack adjuster Replace slack adjuster
(See “Brake
System Maintenance” on
page 4-16.)
Leaking brake chamber diaphragm Replace diaphragm.
BRAKES APPLY TOO SLOWLY Brakes need adjusting or lubrication Adjust or lubricate as needed.
Low air pressure in brake system (below
105 PSI)
Check tractor air system.
Restricted tubing or hose Locate restriction and remove.
Defective relay valve Clean or replace.
Call Factory or see qualified Trailer/Brake Technician
BRAKES RELEASE TOO SLOWLY Brakes need adjusting or lubrication Adjust or lubricate as needed.
Brake rigging binding Align brakes or replace bent parts.
Exhaust port of relay valve restricted or
plugged
Clean valve.
Tractor pressure too low Adjust to provide 105 psi min.
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