4-14. 12-VOLT ELECTRICAL SYSTEM TROUBLESHOOTING PROCEDURES (CONT).
13. REAR MARKER LIGHT(S) DO NOT OPERATE (S/N YB6122 075 AND UP).
Tools and Special Tools
Tool Kit, General Mechanic's: Automotive
(Item 50, Appendix J)
Multimeter (Item 28, Appendix J)
Engine OFF, (TM 9-2320-364-10)
Wheels chocked, (TM 9-2320-364-10)
12 vdc cable assembly connected to truck,
Parking brake applied, (TM 9-2320-364-10)
The following troubleshooting procedures cover one rear marker light, but they apply to all rear marker lights.
All electrical wires and components listed in this troubleshooting procedure are illustrated and located in FO-1.1.
Truck electrical system OK.
Does at least one rear or rear
All other trailer lights operate.
side marker light operate when
power is applied?
REASON FOR QUESTION
If no rear or rear side marker
Wire 1012B faulty.
lights operate, fault is in trailer
Wire 1435 faulty.
main wire harness 1012B. If at
Marker light faulty.
least one rear or rear side mark-
er light operates, fault is in rear
junction box through rear mark-
Repair wire 1012B
(see schematic, Fig
FO-1.1) or replace
trailer main wire
harness (Para 4-30.1).
Verify repair, go to
Step 4 of this Fault.