TM 9-2320-363-20-1
Table 3-1.
Troubleshooting
(Cont)
Malfunction
Test
or Inspection
Corrective Action
ELECTRICAL SYSTEM (CONT)
Blackout Light Circuits (Cont)
6.
NONE
OF THE
BLACKOUT
(B/O)
DRIVE
LIGHTS
OPERATE.
Step
1.
Inspect
light
bulbs.
.
Replace
if broken
or
defective
(page
4-211).
Step
2.
Disconnect
B/O drive lights relay from connector.
Check
for +24
VDC
at
connector
30.
.
If +24
VDC
is present,
go to step 3. If no voltage
is present,
repair lead 421 V (page 3-2).
Step 3.
Check
for +24 VDC
at connector
85.
.
If +24
VDC
is present,
go to step 4. If no voltage
is present,
repair lead 4200
(page 3-2).
Step 4.
Check
for continuity
between
connector 86 and ground.
.
If continuity is indicated,
go to step 5. If no continuity
is
indicated,
repair ground lead (page
3-2).
Step
5.
Install jumper
wires
between
connector 30 and stoplights
relay,
connector
85
and
stoplights
relay,
and connector 86 and stoplights relay.
Check
for
+24
VDC
at stoplights
relay contact 87.
.
If +24
VDC
is present,
repair
lead
421P
or
lead
421 K
(page
3-2).
If no
voltage
is present,
replace
B/O
drive
lights
relay
(pages
4-197,
4-198).
7.
ONE
OR
MORE
BLACKOUT
(B/O)
DRIVE
LIGHTS
NOT OPERATING.
Step
1.
Inspect
light bulb(s).
.
Replace
if broken or defective
(page
4-211).
Step 2.
Remove
lamp from defective
circuit (page 4-211).
Check
for continuity
between
socket
and ground.
.
If continuity is indicated,
go to step 3. If no continuity
is
indicated,
replace
lamp (page 4-21 1).
Step 3.
Disconnect
ground (B/O)
drive lights. Check for continuity
between
ground
lead(s)
and ground.
.
If continuity
is indicated,
repair lead 421P
(page
3-2).
If no
continuity
is indicated,
repair ground lead(s)
(page
3-2).
Step 4.
Check
for +24
VDC
at connector
421 K at trailer receptacle(s).
.
If +24
VDC
is
present,
troubleshoot
trailer
circuit(s).
If
no
voltage
is
present,
repair
lead(s)
421 K
(page
3-2).
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