TM 9-2320-273-20
Table 5-13. Blackout Lighting System Circuit Troubleshooting.
INSTRUCTION
INDICATION
YES
NO
REMARKS
NOTE
The following procedures assume that:
a. Normal service lighting system functions
properly (if not; refer to para 5-14).
b. OPERATION switch is in BLACKOUT
position.
1
ALL BLACKOUT LAMPS INOPERATIVE.
Replace OPERATION
switch.
2
ONE BLACKOUT MARKER, HEADLAMP, TAIL LAMP OR STOP LAMP INOPERATIVE.
1
Replace bulb.
Lamp goes on,
Go to
Step 2.
2 Check for voltage at
12V nominal available
Inspect
lamp connector; then
at one test point; not
wiring be-
work back to OPERA- available at preceding
tween points
TION switch checking test point.
checked;
for voltage at each
then replace
wire connector.
defective
wire(s).
3
TRAILER BLACKOUT LAMPS INOPERATIVE.
1
Check for voltage at
24V nominal available
Inspect
Go to
trailer applicable
at one test point; not
wiring be-
Step 2.
connector pin (A or
available at preceding
tween points
F); then work back to
test point.
checked;
output of relay (K4
then replace
or K5) checking for
defective
voltage at each wire
wire(s).
connection.
2 Check for voltage at
12V nominal.
Go to
Go to
If power is available,
input of relay coil
Step 3.
Step 4.
(K4 or K5).
problem is in relay
or 24V circuit from
starter solenoid. If
power is not avail-
able, problem is in
relay or 12V circuit
from OPERATIONS
switch. Check relay
as described in para.
5-5C.
5-57
