ALL TRAILER LIGHTS DO NOT OPERATE (S/N YB6122 075 AND UP). -725550490

TM 9-2330-385-14

4-14. 12-VOLT ELECTRICAL SYSTEM TROUBLESHOOTING PROCEDURES (CONT).

20. ALL TRAILER LIGHTS 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)

12 vdc cable assembly connected to truck,

(Para 2-9)

Personnel Required

Two

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

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

NOTE

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

START

KNOWN INFO

TEST OPTIONS

WARNING

Read WARNING

Continuity test.

Truck electrical system OK.

on Page 4-202.65

REASON FOR QUESTION

POSSIBLE PROBLEMS

Is continuity measured

If continuity is not measured

12 vdc cable faulty.

between 12 vdc cable

between 12 vdc cable, pin A

Wire 1435 faulty.

and a known good ground, 12

connector, pin A and a known

vdc cable is faulty.

good ground?

If continuity is measured, trailer

harness wire 1435 is faulty.

Repair (Para 4-31) or

replace (Para 2-9)12

vdc cable. Verify

repair, go to

Step 2 of this Fault.

YES

Repair wire 1435

(see schematic, Fig

FO-1.1) or replace

trailer main wire

harness (Para 4-30.1).

Verify repair go to

Step 2 of this Fault.

4-202.64