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 318 of 1417
NG81: BATTERY TESTS - Continued
NOTE
•
Test each battery of a series pair, then proceed to batteries of next series pair.
•
To find series pair of batteries is connected by a cable to positive terminal of another
battery. This makes two batteries a series pair. For example, in figure below,
batteries A and B are a series pair, and batteries C and D are also a series pair.
•
To test battery A or B, clamp current probe around cable connecting battery A and
battery B. Point arrow on current probe in direction of negative post connected to
cable.
•
Test probe cable W2 is first connected to battery A for testing battery A.
•
Test probe cable W2 is first connected to battery B for testing battery B.
(Current probe in same place as for testing battery A.)
•
To test battery C or D, clamp current probe around cable connecting battery C and
battery D. Point arrow on current probe in direction of negative post connected to
cable.
•
Test probe cable W2 is first connected to battery C for testing battery C.
•
Test probe cable W2 is first connected to battery D for testing battery D.
e.
Clamp probe around battery cable which connects series pair of batteries containing battery to be tested.
Point arrow on current probe toward negative post connected to battery cable, as shown.
f.
Attempt to crank engine for several cycles.
g.
Turn off all vehicle electrical power.
h.
Dial 90 into TEST SELECT.
i.
Press and hold TEST until CAL message appears on the display.
T0021DAA
Figure 3.
CAL Prompting Message.
j.
Release TEST.
k.
Wait for offset value to appear.
CONDITION/INDICATION
Is offset value within limits of -225 to +225?
DECISION
YES - Go to Step (3).
NO - Proceed to TM 9-4910-571-12&P for offset fault isolation.
TM 9-2320-272-23-2
0203
0203-3
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