Organizational Troubleshooting Table
TEST OR INSPECTION
BRAKES WILL NOT RELEASE - continued.
Check for weak or broken brake shoe tension spring.
If brake shoe tension spring is broken, replace (para. 4-42) .
NO BRAKES OR WEAK BRAKES.
Check for closed shutoff valves on towing vehicle.
Open valves, if closed.
If valves are open, go to step 2.
Check air hoses for proper connection to towing vehicle.
Connect hoses properly.
If hoses are properly connected, go to step 3.
Check for open drain cocks in semitrailer air reservoirs.
Close drain cocks, if open.
If drain cocks are closed, go to step 4.
Check air pressure gage on towing vehicle for low air pressure
indication. Check air lines/connectors for restrictions.
Tighten connections; remove any restrictions from hoses.
If air pressure gage indicates normal, go to step 5.
Check for defective emergency relay valve.
If emergency relay valve is not defective, go to step 6.
Check for grease on brake lining.
If brake lining has grease on it, replace brake shoes (para.
If brake lining shows no grease, go to step 7.