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 1121 of 1313
SECONDARY AIR SYSTEM FAILS TO MAINTAIN PRESSURE (NO MAJOR LEAKS, AIR CAN BE HEARD
ESCAPING INTO AIR INTAKE STACK, PARKING BRAKE APPLIED) - Continued
STEP
1.
IS PROPER AIR PRESSURE AT SECONDARY RELAY VALVE?
a.
Stop engine and open all draincocks until brake system air pressure is vented.
b.
Close all draincocks.
T0286DAA
Delivery
Line
Delivery
Port
Elbow
Transducer
Relay
Valve
Figure 1.
Secondary Relay Valve Delivery Port.
c.
Disconnect air line from elbow at secondary relay valve delivery port (Volume 3, WP
0457). Refer to
point to point schematics.
d.
Remove elbow from secondary relay valve delivery port.
e.
Connect pressure gauge to disconnected relay valve delivery port.
f.
Assistant starts engine and runs to build air supply to normal operating pressure.
g.
Assistant fully applies and holds service brakes.
h.
Monitor air pressure on pressure gauge.
i.
After 5 minutes, pressure gauge should read 90 to 130 psi.
TM 9-2320-272-23-1
0133
0133-2
Back to Top
