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 305 of 1417
NG50: CHARGING CIRCUIT TESTS - Continued
STEP
2.
Perform charging system test.
a.
Start vehicle engine.
b.
Turn on vehicle lights.
c.
Set engine speed to fast idle.
d.
Dial 89 into TEST SELECT and press TEST.
Table
1.
Voltage Test.
TEST NO.
TEST
89
Alt/Gen Output Voltage
CONDITION/INDICATION
Is reading between 26.5 and 29.5 VDC?
DECISION
YES - Repair bad connections or broken cables in charging system output (WP
0349) and ground circuits
(WP
0350). If problem still exists, replace alternator M939/A1
60 amp (WP
0300), M939A2 60 amp (WP
0301), 100 amp (Volume 5, WP
0780). After completing repair, rerun
GO-Chain tests to verify problem is solved and no other problem exists.
NO - Go to NG80: Starter Circuit Test (WP
0202).
END OF WORK PACKAGE
TM 9-2320-272-23-2
0201
0201-2
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