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 1070 of 1313

FIELD MAINTENANCE

WARNING BUZZER SOUNDS WHEN BRAKES ARE APPLIED (PRIMARY & SECONDARY GAUGE PRESSURE

DROPS BELOW 55-65 PSI [379-448 KPA])

INITIAL SETUP:

Tools and Special Tools

Tool Kit, General Mechanic's: Automotive

(Volume 5, WP

0826, Table 1, Item 56)

Test Set, Electronic Systems

(Volume 5, WP

0826, Table 1, Item 51)

Personnel Required

(2)

References

Point to Point Schematics

Volume 5, WP

0805

Equipment Condition

Vehicle parked and engine shut down.

(TM

9-2320-272-10)

TROUBLESHOOTING PROCEDURE

WARNING BUZZER SOUNDS WHEN BRAKES ARE APPLIED (PRIMARY & SECONDARY GAUGE PRESSURE

DROPS BELOW 55-65 PSI [379-448 KPA])

NOTE

Conduct these malfunction tests if warning buzzer sounds when brakes are applied and

primary and secondary gauge pressure drops below 55-65 psi. This procedure will check for

air leaks in air delivery components.

STEP

1.

IS THERE EVIDENCE OF AN AIR LEAK FROM A BRAKE SYSTEM COMPONENT?

a.

Start engine and run to build air supply to normal operating pressure.

b.

Assistant fully applies service brakes.

c.

Listen for and locate any air leaks. Refer to point to point schematics.

CONDITION/INDICATION

IS THERE EVIDENCE OF AN AIR LEAK FROM A BRAKE SYSTEM COMPONENT?

DECISION

YES - Replace damaged air lines (Volume 5, WP

0805). Go to Step (2) to verify problem is solved.

NO - Go to Step (2) to verify problem is solved.

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