BLACKOUT STOPLIGHT(S) DO NOT OPERATE (S/N YB6122 075 AND UP).

TM 9-2330-385-14

4-13. 24 VOLT ELECTRICAL SYSTEM TROUBLESHOOTING PROCEDURES (CONT).

18. BLACKOUT STOPLIGHT(S) DO NOT OPERATE (S/N YB6122 075 AND UP).

INITIAL SETUP

Tools and Special Tools

References

Tool Kit, General Mechanic's: Automotive

TM 9-2320-364-10

(Item 50, Appendix J)

Equipment Condition

Multimeter (Item 28, Appendix J)

Engine OFF, (TM 9-2320-364-10)

24 vdc cable assembly connected to truck,

Personnel Required

(Para 2-9)

Two

Parking brake applied, (TM 9-2320-364-10)

Truck air pressure charged, (TM 9-2320-364-10)

Wheels chocked, (TM 9-2320-364-10)

NOTE

The following troubleshooting procedures cover the left blackout stoplight, but they apply to both blackout stoplights.

All electrical wires and components listed in this troubleshooting procedure are illustrated and located in Figure FO-1.1.

START

KNOWN INFO

TEST OPTIONS

Truck electrical system OK.

Visual inspection.

Does at least one blackout

All other trailer lights operate.

stoplight operate when

Taillights operate indicating

REASON FOR QUESTION

brakes are applied?

LED composite light ground

If no blackout stoplights operate,

(wire 1435) OK.

fault is 24 vdc cable assembly

POSSIBLE PROBLEMS

through wire 1678C. If at least

one stoplight operates, fault is

rear junction box through LED

Wire 1678C/23 faulty.

composite light.

Wire 1678C faulty.

LED composite light faulty.

Go to Step 3 of this

Fault.

YES

4-118.46