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 841 of 1313
INDIVIDUAL LIGHTS DO NOT LIGHT WITH DIRECTIONAL SIGNAL LEVER IN ANY POSITION - Continued
STEP
3.
IS THERE CONTINUITY THROUGH WIRE THAT CONNECTS TO FAULTY LAMP?
a.
Place battery switch to OFF position.
b.
Jumper disconnected wire to a known good ground.
T0778DAA
VOM
A
B
C
E
LH
LH
RH
RH
REAR
COMPOSITE
LIGHT
REAR
COMPOSITE
LIGHT
CONTROL
UNIT
HARNESS
CONNECTOR
FRONT
COMPOSITE
LIGHT
FRONT
COMPOSITE
LIGHT
LIGHT SWITCH
OFF
POSITION
Figure 3.
Directional Signal Circuit Test.
c.
Disconnect wire connector from control unit.
d.
Set up multimeter to measure resistance.
e.
Near control unit, connect multimeter black lead to good ground.
f.
If wire 461 is disconnected, connect multimeter red lead to circuit 461 wire at socket point B. Refer to
point to point schematics.
g.
If wire 460 is disconnected, connect multimeter red lead to circuit 460 wire at socket point A.
h.
If wire 22-461 is disconnected, connect multimeter red lead to circuit 22-461 wire at socket point C.
i.
If wire 21-460 is disconnected, connect multimeter red lead to circuit 21-460 wire at socket point E.
j.
Meter reading should be less than 20 ohms.
CONDITION/INDICATION
IS THERE CONTINUITY THROUGH WIRE THAT CONNECTS TO FAULTY LAMP?
DECISION
NO - Repair broken wire (Volume 3, WP
0352). Go to Step (5) to verify problem is solved.
YES - Go to Step (4).
TM 9-2320-272-23-1
0097
0097-4
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