TM10-3930-660-20 Table  2-2. Electrical  Troubleshooting  (Cont’d) MALFUNCTION TEST OR INSPECTION CORRECTIVE  ACTION Step 2. Check for defective horn button or wires. Test horn button and wires for continuity, para. 8-46. Step 3. Check for defective horn. Test horn, replace if necessary, para. 8-42. Step 4. Check blackout light switch. Replace switch if defective, para. 8-14. 12. BACKUP ALARM DOES NOT SOUND Step 1. Check if circuit breaker (CB2) is tripped. l The circuit breakers will trip if there is a shorted or grounded wire. l The  circuit  breakers  will  automatically  reset  after  cooling.  They cannot be reset manually. . Under normal operating conditions, circuit breakers should never require replacement. However, if a circuit breaker does not reset after it has cooled, the circuit breaker is defective and must be replaced, para. 8-12. Check backup alarm circuit for shorts, broken wire, or bad ground. Refer to electrical schematic, page F/O-l. Step 2. Check for defective backup alarm switch, broken switch wires, or loose connections. Check switch and switch wires for continuity, para. 8-46. Replace defective switch, para. 8-41, or broken wire, para. 8-46, if necessary. Step 3. Check for defective backup alarm. Test backup alarm. Replace if defective, para. 8-40. Step 4. Check for defective blackout light switch. Replace switch if defective, para. 8-14. 2-18