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 0006 00 0006 00-26 MECHANICAL SYSTEMS TROUBLESHOOTING - UNIT (Contd) Table 21. Personnel Fuel Burning Heater Troubleshooting Procedures. MALFUNCTION TEST OR INSPECTION CORRECTIVE ACTION 1. HEATER WILL NOT OPERATE IN HIGH OR LOW SWITCH POSITION Test 1. Check horn operation. Push horn button. Test 2. Test lead 10 for power input to heater control box. 1. Set multimeter to range that will measure 24 VDC. 2. Disconnect lead 10 from heater control box. 3. Touch multimeter positive lead to contact end of lead 10. 4. Touch negative lead of multimeter to frame ground. Voltage should be present. Test 3. Check heater control box for power output. 1. Set multimeter to range that will measure 24 VDC. 2. Disconnect harness connector from rear of control box. 3. Set heater control switch to START and hold. 4. Set heater control heat switch to HIGH. 5. Touch positive lead of multimeter to pin A. 6. Touch negative lead of multimeter to frame ground. 7. Repeat steps 5 and 6 for pins B, C, and D. Voltage should be present. 1. If horn is operational, voltage is present at input of personnel heater circuit breaker. Go to test 2. 2. If horn fails to operate, go to WP 0014 00, table 1, malfunction 10. 1. If voltage is present, go to test 3. 2. If voltage is not present, repair or replace lead 10 (WP 0090 00). 1. If voltage is present at all pins tested, go to test 4. 2. If voltage is not present at one or more pins, replace heater control box (WP 0352 00).