TM 9-2320-273-20
Table 9-1. Compressed Air and Brake System Troubleshooting Procedures (Continued).
MALFUNCTION.
TEST OR INSPECTION.
CORRECTIVE ACTION.
6. SERVICE BRAKES WILL NOT APPLY (Continued):
Step 4.
Check for leakage at the brake pedal valve using a soap solution.
Tighten connections or replace defective brake pedal valve (para 9-21).
Step 5.
Check brakes for proper adjustment and worn linings.
Adjust brakes (para 9-31, 9-32, 9-33, 9-34).
7. NO SERVICE BRAKES ON TRAILER OR TOWED VEHICLE ONLY:
Step 1.
Check service air hose connection and position of trailer supply valve.
Reconnect hose properly and open trailer supply valve.
Step 2.
Check trailer supply valve for damage or leakage using a soap solution.
Replace defective valve (para 9-17).
Step 3.
Check the double-check valve(s) for damage or leakage using a soap solution.
Replace defective valve (para 9-27).
Step 4.
Check tractor protection valve for damage or corrosion.
If valve is defective, replace defective valve.
8. TRAILER HAND CONTROL WILL NOT APPLY TRAILER SERVICE BRAKES:
Step 1.
Check air lines between trailer hand control and double check valve for leakage using
a soap solution.
Repair leaks.
Step 2.
Check tractor protection valve for damage or leaks using a soap solution.
Tighten connections or replace valve (para 9-26).
Step 3.
Check the double-check valve for damage or leaks using a soap solution.
Tighten connections or replace valve (para 9-27).
9. PARK BRAKES WILL NOT APPLY:
Step 1.
Inspect vent on the park brake valve for damage or clogging.
Clean vent or replace valve (para 9-19).
Change 2
9-5
