TM 9-2320-272-24-1
Table 2-4. Compressed
and Brake System Troubleshooting (Contd).
Air
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
13. PRIMARY PRESSURE GAUGE READS NO PRESSURE, LOW PRESSURE, OR BUILDS TO NORMAL OPERATING
PRESSURE SLOWLY. SECONDARY PRESSURE GAUGE READS NORMAL (ENGINE IDLING, BRAKE PEDAL NOT
APPLIED)
Test 1. Check for leaks.
Listen and locate leakage.
a. If leakage is indicated, repair or replace air lines or fittings as necessary.
b. If no leakage is indicated, perform test 2.
Test 2. Check primary air pressure gauge (3).
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 air line (2) from primary air pressure gauge (3).
Step 4. Connect test gauge to air line (2).
Step 5. Direct assistant to start engine and allow air system to build to normal operating
pressure.
Step 6. Check test gauge reading.
a. If test gauge reads normal operating pressure, replace primary air pressure gauge (3)
b. If test gauge reads no pressure, low pressure, or pressure is building slowly, perform
test 3.
c. Stop engine, drain air, remove test gauge, and connect air line (2).
Test 3. Check air pressure at brake pedal valve supply port (7).
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 primary pressure gauge air line (5) from pedal valve (4).
Step 4. Connect test gauge to supply port (6) of pedal valve (4).
Step 5. Direct assistant to start engine and allow air system to build to normal operating
pressure.
Step 6. Check test gauge reading.
a. If test gauge reads normal operating pressure, repair or replace clogged primary
pressure gauge air line (5).
b. If test gauge reads no pressure, low pressure, or pressure is building slowly, perform
test 4.
c. Stop engine, drain air, remove test gauge, and connect air line (5).
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