TM-9-2320-272-23-2

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

TECHNICAL MANUAL; FIELD MAINTENANCE MANUAL; VOLUME 2 OF 5

SEPTEMBER 2012

TM-9-2320-272-23-2 - Page 325 of 1417

NG90: GOVERNOR/POWER TEST FAULT ISOLATION - Continued

STEP

2.

Perform air cleaner pressure drop test

a.

Reinstall air cleaner (WP

0245).

CAUTION

Do not perform more than 2 compression unbalance tests in a row to prevent discharge

of vehicle batteries.

Engine must be at normal operating temperature before performing compression

unbalance test.

NOTE

The compression unbalance test takes approximately 15 seconds to run.

b.

Dial 28 into TEST SELECT and press TEST.

c.

Hold engine at high idle.

CONDITION/INDICATION

Is air cleaner pressure drop less than 10 in. (25.4 cm) of water?

DECISION

YES - Go to Step (3).

NO - Replace air filter

(WP

0246). Repeat G06: Power Test Step (2) to verify this was the only fault

(WP

0193).

TM 9-2320-272-23-2

0204

0204-2