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 1120 of 1313

FIELD MAINTENANCE

SECONDARY AIR SYSTEM FAILS TO MAINTAIN PRESSURE (NO MAJOR LEAKS, AIR CAN BE HEARD

ESCAPING INTO AIR INTAKE STACK, PARKING BRAKE 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

0429

Volume 3, WP

0430

Volume 3, WP

0457

Volume 5, WP

0805

Equipment Condition

Vehicle parked and engine shut down.

(TM

9-2320-272-10)

TROUBLESHOOTING PROCEDURE

SECONDARY AIR SYSTEM FAILS TO MAINTAIN PRESSURE (NO MAJOR LEAKS, AIR CAN BE HEARD

ESCAPING INTO AIR INTAKE STACK, PARKING BRAKE APPLIED)

NOTE

Conduct these malfunction tests if secondary air pressure system fails to hold pressure. No

major leaks, air can be heard escaping into air intake stack, parking brake applied. This

procedure will check for blocked secondary air system relay valve and secondary air pressure

gauge delivery lines.

TM 9-2320-272-23-1

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