TM-9-2320-361-24-1 Field Maintenance Manual Volume 1 for M44A2 Series Trucks
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TM 9-2320-361-24-1 0014 00 0014 00-18 INDICATORS, GAUGES, AND WARNING SYSTEM TROUBLESHOOTING (Contd) Table 1. Indicator, Gauges, and Warning System Troubleshooting (Contd). MALFUNCTION TEST OR INSPECTION CORRECTIVE ACTION 10. HORN DOES NOT OPERATE NOTE Troubleshooting of the electrical horn and air horn are the same. Test 1. Test input voltage to horn circuit breaker. 1. Turn main light switch to SERVICE DRIVE position. 2. Remove lead 25 from circuit horn breaker. 3. Set multimeter to a voltage range that will measure 24 VDC. 4. Connect negative lead to frame ground. 5. Touch positive lead to horn circuit breaker contact. Test 2. Test air horn solenoid. 1. Remove lead 25 from pin B of air horn solenoid. 2. Connect negative lead of multimeter to frame ground. 3. Touch positive lead to pin B of solenoid. 4. Remove lead 25 connected to pin A of air horn solenoid. Connect negative lead to frame ground. Touch positive lead to contact end of lead 25. Test 3. Test horn switch input voltage. 1. Remove horn button (WP 0113 00) until lead 25 can be seen. 2. Set multimeter to a voltage range that will measure 24 VDC. 3. Connect negative lead to frame ground. 4. Touch positive lead to lead 25 contact end. 1. If voltage is not present, replace horn circuit breaker. 2. If voltage is present, go to test 2. 1. If voltage is present, go to test 3. 2. If voltage is not present, go to step 4. 1. If voltage is present, replace air horn solenoid (WP 0114 00). 2. If voltage is not present, repair or replace lead 25. 1. If voltage is not present, repair or replace lead 25 (WP 0090 00). 2. If voltage is present, go to test 4.