TM 9-2320-364-20-2 2-1410 29.  HORN DOES NOT OPERATE (CONT). 4. Repair wire 1026 (see schematic Fig 2-36) or notify DS Maintenance.   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 faulty. Wire 1031 faulty. 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 Voltage test. STE/ICE-R #89. If 22 to 28 vdc are not present, wire 1026 is faulty. WARNING 5. Repair wire 1031 (see schematic Fig 2-36) or notify DS Maintenance.   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 faulty. 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 Voltage test. STE/ICE-R #89. If 10 to 14 vdc are not present, wire 1031 is faulty. WARNING Are 22 to 28 vdc measured on wire 1026 at horn relay R3, terminal 30? Are 10 to 14 vdc measured on wire 1031 at horn relay R3, terminal 85? Read   WARNING on Page 2-1411 Read   WARNING on Page 2-1411