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 842 of 1313
INDIVIDUAL LIGHTS DO NOT LIGHT WITH DIRECTIONAL SIGNAL LEVER IN ANY POSITION - Continued
STEP
4.
IS THERE A SHORT IN THE WIRING HARNESS?
a.
Remove jumper from disconnected wire and 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 4.
Directional Signal Circuit Test.
b.
Near control unit, connect multimeter black lead to good ground.
c.
If wire 461 is disconnected, connect multimeter red lead to circuit 461 wire at socket point B. Refer to
point to point schematics.
d.
If wire 460 is disconnected, connect multimeter red lead to circuit 460 wire at socket point A.
e.
If wire 22-461 is disconnected, connect multimeter red lead to circuit 22-461 wire at socket point C.
f.
If wire 21-460 is disconnected, connect multimeter red lead to circuit 21-460 wire at socket point E.
g.
Meter reading should be greater than 10,000 ohms.
CONDITION/INDICATION
IS THERE A SHORT IN THE WIRING HARNESS?
DECISION
YES - Repair frayed, or pinched wire (Volume 3, WP
0352). Go to Step (5) to verify problem is solved.
NO - Perform No Lights Operate With Directional Signal Lever In Any Position (WP
0098) troubleshooting.
TM 9-2320-272-23-1
0097
0097-5
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