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 368 of 926

TM 9-2320-283-20-1

TROUBLESHOOTING.

2-11.

TROUBLESHOOTING PROCEDURES (Continued).

MALFUNCTION

INSTRUCTION

INDICATION

YES

NO

80.

BOTH 24-VOLT TRAILER BLACKOUT STOPLAMPS NOT WORKING.

NOTE

-Blackout toggle switch must be set to BLACKOUT position, air system pressurized to

105 psi, and brake pedal depressed by assistant when doing the following check.

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

·Do steps 1 thru 17 when troubleshoot- ing 24-volt cab connector.

·Do steps 1 thru 15 and steps 18 and 19

when

troubleshooting

24-volt chassis

connector.

1

Check for voltage at 12-volts dc

Go to step 2

Replace black-

circuit 24D-PK terminal

nominal

out toggle

of blackout toggle

switch (para

switch

3-79).

2

Remove circuit breaker

bracket far enough to

access relay RY-4 and

relay connector (para

3-114), and go to step

3.

3

Remove relay RY-4 (para

3-112), and go to step

4.

2-242