TM 9-2320-364-20-2 2-1532 41.  TRAILER MARKER LIGHTS DO NOT OPERATE (CONT). Trailer brake lights operate   indicating that wire 1435 at   connector MC15 is OK. 22 to 28 vdc supplied to   connector MC15. Wire 1676 OK. Wire 1017 OK. Wire 1435 OK. Relay R14 faulty. Wire 1008C faulty. KNOWN INFO POSSIBLE PROBLEMS TEST OPTIONS REASON FOR QUESTION Voltage test. STE/ICE-R #89. If 22 to 28 vdc are not present, relay R14 is faulty. YES NO Replace trailer service lights relay R14 (Para 7-95). Verify repair, go to Step 6 of this Fault. 5. Are 22 to 28 vdc measured on wire 1008C at trailer service lights relay R14, terminal 87? Repair wire 1008C (see schematic Fig 2-35) or notify DS Maintenance. Verify repair, go to Step 6 of this Fault. 4. Repair wire 1435 (see schematic Fig 2-35) or notify DS Maintenance. Verify repair, go to Step 6 of this Fault. YES NO Trailer brake lights operate   indicating that wire 1435 at   connector MC15 is OK. 22 to 28 vdc supplied to   connector MC15. Wire 1676 OK. Wire 1017 OK. Wire 1435 faulty. Relay R14 faulty. Wire 1008C faulty. KNOWN INFO POSSIBLE PROBLEMS TEST OPTIONS REASON FOR QUESTION Continuity test. STE/ICR-R #91. Trailer service lights relay R14 will not operate if wire 1435 is not grounded. WARNING WARNING Is continuity measured on wire 1435 between trailer service lights relay R14, terminal 85 and a known good ground? Read   WARNING on Page 2-1533 Read   WARNING on Page 2-1533