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 1098 of 1313

FIELD MAINTENANCE

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)

INITIAL SETUP:

Tools and Special Tools

Tool Kit, General Mechanic's: Automotive

(Volume 5, WP

0826, Table 1, Item 56)

Gauge, Pressure

(Volume 5, WP

0826, Table 1, Item 19)

Test Set, Electronic Systems

(Volume 5, WP

0826, Table 1, Item 51)

Personnel Required

(2)

References

Point to Point Schematics

References (cont.)

Volume 3, WP

0428

Volume 3, WP

0429

Volume 3, WP

0430

Volume 5, WP

0805

Volume 5, WP

0818

Equipment Condition

Vehicle parked and engine shut down.

(TM

9-2320-272-10)

TROUBLESHOOTING PROCEDURE

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)

NOTE

Conduct these malfunction tests if primary air pressure gauge reads no pressure, low

pressure or builds slowly to normal operating pressure, secondary air pressure gauge reads

normal. This procedure will check for air leaks from lines or fittings, faulty primary air pressure

gauge, clogged air supply lines, faulty brake pedal valve or one-way check valve.

TM 9-2320-272-23-1

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