TM-9-2320-272-24-1

TRUCK, 5-TON, 6X6, M939, M939A1, AND M939A2 SERIES TRUCKS (DIESEL)

TECHNICAL MANUAL; UNIT, DIRECT SUPPORT, AND GENERAL SUPPORT MAINTENANCE MANUAL; VOLUME 1 OF 4

JUNE 1998

TM-9-2320-272-24-1 - Page 638 of 1015

3-99. PRIMARY

TM 9-2320-272-24-1

THIS TASK COVERS:

a. Primary Switch Removal

c. Secondary Switch Removal

b. Primary Switch Installation

d. Secondary Switch Installation

INITIAL SETUP:

APPLICABLE MODELS

EQUIPMENT CONDITION

All

TOOLS

General mechanic’s tool kit (Appendix E, Item 1)

MATERIALS/PARTS

Antiseize tape (Appendix C, Item 72)

REFERENCES (TM)

TM 9-2320-272-10

TM 9-2320-272-24P

Parking brake set (TM 9-2320-272-10).

Air reservoirs drained (TM 9-2320-272-10).

Battery ground cables disconnected (para. 3-126).

GENERAL SAFETY INSTRUCTIONS

Do not disconnect air lines before draining

reservoirs.

Exhaust system components are hot.

WARNING

Do not disconnect air lines before draining air reservoirs. Small

parts under pressure may shoot out with high velocity, causing

injury to personnel.

Do not touch hot exhaust system components with bare hands.

Injury to personnel may result.

NOTE

Tag wires for installation.

1.

Disconnect wires (1) and (2) from primary low air pressure switch (5).

2.

Remove low air pressure switch (5) and adapter fitting (4) from adapter elbow (3).

NOTE

Male pipe threads must be wrapped with antiseize tape before

installation

1.

Install adapter fitting (4) and low air pressure switch (5) on adapter elbow (3).

2.

Connect wires (2) and (1) to primary low air pressure switch (5).

3-274