TM-9-2320-283-20-1

TRUCK TRACTOR, LINE HAUL, 50,000 GVWR, 6X4, M915A1

TECHNICAL MANUAL; ORGANIZATIONAL MAINTENANCE PART 1 OF 3

DECEMBER 1983

TM-9-2320-283-20-1 - Page 378 of 926

TM 9-2320-283-20-1

TROUBLESHOOTING.

2-11.

TROUBLESHOOTING PROCEDURES (Continued).

MALFUNCTION

INSTRUCTION

INDICATION

YES

NO

81.

24-VOLT TRAILER BLACKOUT TAILLAMPS NOT WORKING.

NOTE

.Headlamp switch must be in ON position and blackout toggle switch set to BLACKOUT

position when doing the fol- lowing checks.

·It is assumed here that chassis tail- lamp circuit is OK.

-Do steps 1 thru 23 when troubleshoot- ing 24-volt cab connector.

·Do steps 1 thru 21 and steps 24 and 25 when troubleshooting 24-volt chassis

connector.

1

Check for voltage at 12-volts dc

Go to step 2

Replace black-

circuit 23Z-TN blackout

nominal

out toggle

toggle switch

switch (para

3-79)

2

Remove circuit breaker

bracket far enough to

access relay RY-5 and

relay connector (para

3-114), and go to step

3.

3

Remove relay RY-5 (para

3-112), and go to step

4.

2-252