TM 9-2320-364-20-2 2-1412 29.  HORN DOES NOT OPERATE (CONT). 6. Is continuity measured between horn button and cancel ring? Replace faulty horn button components (Para 14-4). Verify repair, go to Step 11 of this Fault. YES NO Reverse lights operate   indicating circuit breaker CB3   OK. Cab heater operates indicating   22 to 28 vdc is input to circuit   breaker CB16. Circuit breakers CB3 and CB16   are not tripped. Horn grounded. Circuit breaker CB16 OK. Wire 1026 OK. Wire 1031 OK. Horn button faulty. Steering column ground faulty. Wire 1016 faulty. Harness wire 1016 faulty. Horn relay R3 faulty. Wire 1168 faulty. KNOWN INFO POSSIBLE PROBLEMS TEST OPTIONS REASON FOR QUESTION Continuity test. STE/ICE-R #91. If there is no continuity, the horn will not operate. WARNING 7. Is continuity measured between steering column and a known good ground? Repair wire 1435 (see schematic Fig 2-36). Verify repair, go to Step 11 of this Fault. YES NO Reverse lights operate   indicating circuit breaker CB3   OK. Cab heater operates indicating   22 to 28 vdc is input to circuit   breaker CB16. Circuit breakers CB3 and CB16   are not tripped. Horn grounded. Circuit breaker CB16 OK. Wire 1026 OK. Wire 1031 OK. Horn button OK. Steering column ground faulty. Wire 1016 faulty. Harness wire 1016 faulty. Horn relay R3 faulty. Wire 1168 faulty. KNOWN INFO POSSIBLE PROBLEMS TEST OPTIONS REASON FOR QUESTION Continuity test. STE/ICE-R #91. If there is no continuity, wire 1435 is faulty. Read   WARNING on Page 2-1413