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 1113 of 1313
SECONDARY PRESSURE GAUGE READS NO PRESSURE, LOW PRESSURE, OR BUILDS TO NORMAL
OPERATING PRESSURE SLOWLY. PRIMARY PRESSURE GAUGE READS NORMAL (ENGINE IDLING,
BRAKE PEDAL NOT APPLIED) - Continued
STEP
5.
IS THERE PROPER AIR PRESSURE AT BRAKE PEDAL VALVE?
a.
Stop engine and open all draincocks until brake system air pressure is vented.
b.
Close draincocks.
Secondary Air System
Supply Line
T0282DAA
Figure 5.
Secondary Air System Supply Line.
c.
Disconnect pressure gauge from vehicle return air line to original condition.
d.
Disconnect secondary air system supply line from brake pedal valve fitting. Refer to point to point
schematics.
e.
Connect pressure gauge to secondary supply line.
f.
Start engine.
g.
Monitor air pressure on pressure gauge.
h.
After 5 minutes pressure gauge should be read 90 psi.
CONDITION/INDICATION
IS THERE PROPER AIR PRESSURE AT BRAKE PEDAL VALVE?
DECISION
NO - Go to Step (6).
TM 9-2320-272-23-1
0131
0131-8
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