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 963 of 1313
HEATER WILL NOT OPERATE WITH SWITCH IN HIGH POSITION (LOW POSITION OPERATION NORMAL) -
Continued
STEP
1.
DOES CIRCUIT 5C WIRE SUPPLY PROPER VOLTAGE TO HEATER SWITCH?
a.
Check for battery voltage at circuit 5C wire.
b.
Place battery switch to OFF position.
T0130DAA
569A
400
5C
Figure 1.
Heater Switch Wiring.
c.
Disconnect circuit 5C wire from heater switch.
d.
Place battery switch to ON position.
e.
Set up multimeter to measure VDC.
f.
Connect multimeter red lead to the disconnected end of circuit 5C wire. Refer to point to point schematics.
g.
Connect multimeter black lead to vehicle chassis ground.
h.
Meter reading should be greater than 18 VDC.
CONDITION/INDICATION
DOES CIRCUIT 5C WIRE SUPPLY PROPER VOLTAGE TO HEATER SWITCH?
DECISION
NO - Go to Step (2).
YES - Replace heater switch (Volume 2, WP
0307). Go to Step (4) to verify problem is solved.
TM 9-2320-272-23-1
0115
0115-2
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