TM 9-2320-272-24-1
Table 2-4. Compressed Air and Brake System Troubleshooting (Contd).
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
Test 13. Check primary air tank to relay valve supply line (3) (all four primary air system service
brake chambers test low or nonexistent air pressure).
Step 1. Stop engine and open all drainvalves (1), in sequence shown, until brake system air
pressure is vented.
Step 2. Close drainvalves (1).
Step 3. Disconnect supply line (3) from primary air system relay valve (2).
Step 4. Connect test gauge to supply line (3).
Step 5. Direct assistant to start engine and allow air system to build to normal operating
pressure.
Step 6. Direct assistant to fully apply and hold service brakes.
Step 7. Check reading on test gauge.
a. If pressure is below normal, inspect supply line (3) for blockage. Repair or replace as
necessary.
b. If pressure is normal, replace defective primary air system relay valve (2) (para. 3-187
or 3-188).
c. Stop engine, drain air, remove test gauge, and connect supply line (3).
DRAINVALVE SEQUENCE
2-190
