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 964 of 1313
HEATER WILL NOT OPERATE WITH SWITCH IN HIGH POSITION (LOW POSITION OPERATION NORMAL) -
Continued
STEP
2.
IS THERE BATTERY VOLTAGE AT CIRCUIT 27 TERMINAL OF CIRCUIT BREAKER?
a.
Check for battery voltage from circuit breaker.
b.
Place battery switch to OFF position.
c.
Visually inspect circuit 5C and 27 wires for damaged or frayed condition.
T0131DAA
27
5A
Figure 2.
Circuit Breaker Wire 27.
d.
Disconnect circuit 27 wire from circuit breaker.
e.
Place battery switch to ON position.
f.
Connect multimeter red lead to the open circuit 27 terminal on circuit breaker. 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
IS THERE BATTERY VOLTAGE AT CIRCUIT 27 TERMINAL OF CIRCUIT BREAKER?
DECISION
YES - Repair or replace circuit 5C and 27 wire between circuit breaker and heater
switch (Volume 3, WP
0352). Go to Step (4) to verify problem is solved.
NO - Go to Step (3).
TM 9-2320-272-23-1
0115
0115-3
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