TM-9-2320-272-23-1
TRUCK, 5-TON, 6X6, M939, M939A1, AND M939A2 SERIES TRUCKS (DIESEL)
TECHNICAL MANUAL; FIELD MAINTENANCE MANUAL; VOLUME 1 OF 5
SEPTEMBER 2012
TM-9-2320-272-23-1 - Page 1101 of 1313
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) - Continued
STEP
3.
IS THERE PROPER AIR PRESSURE AT BRAKE PEDAL VALVE SUPPLY PORT?
a.
Stop engine and open all draincocks until brake system air pressure is vented.
b.
Close draincocks.
T0272DAA
Figure 3.
Brake Pedal.
c.
Disconnect primary pressure gauge air line from pedal valve. Refer to point to point schematics.
d.
Connect adapter fitting to pedal valve and move pressure gauge from disconnected air line to adapter
fitting.
e.
Start engine.
f.
Monitor air pressure on pressure gauge.
g.
After 5 minutes pressure gauge should be read 90 psi.
CONDITION/INDICATION
IS THERE PROPER AIR PRESSURE AT BRAKE PEDAL VALVE SUPPLY PORT?
DECISION
NO - Go to Step (4).
YES - Replace damaged air lines (Volume 5, WP
0805). Go to Step (7) to verify problem is solved.
TM 9-2320-272-23-1
0130
0130-4
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