TM-9-2320-280-20 HMMWV Technical Manual Unit Maintenance Volume 1 Download
Page 419 of 890
TM 9-2320-280-20-1 REFERENCE INFORMATION Change 1 2-318.9 Ensure that alternator "AC" tap is functioning correctly by measuring DC volts at wire 2A. Reading should be between 9-16 Vdc. If this voltage is not present, glowplug system will never stop cycling. Refer to the functional flow schematic. If the distribution box is shorted (continuity from pin 6 to pin 3), the glowplug power relay will always be energized and the glowplugs will always be drawing current. Since the glowplugs draw current without the distribution box connected, there must be a short in the harness or a stuck relay in the distribution box. If there were a short in the harness directly to the glowplugs, the glowplugs would have burned out long ago and you wouldn't be here. The only other short in the harness that would make the glowplugs turn on without the distribution box installed would show up as battery voltage at pin 6 of the controller's connector. GLOWPLUGS BATTERY CURRENT MULTIMETER 1. Set the voltmeter to a DC volts scale of about 1 volt. 2. Connect the BLACK lead to the battery side of the current shunt and the RED lead to the other end of the current shunt. 3. Current shunt voltage is proportional to battery current, 100 millivolts = 1000 amps. To get current, multiply millivolts x 10. BATTERY CURRENT STE/ICE-R TEST 80 1. Start Test 80, battery current. 2. Displayed reading is in amps. The reading will be greater then 30 amps, depending on how many accessories you have on. VOLTAGE MULTIMETER 1. Set the voltmeter to a DC volts scale of at least 40 volts. 2. Connect the RED lead to positive and the BLACK lead to negative. 3. Be sure to read the correct scale. Check the end of the harness at the distribution box, glowplugs, etc. for shorts. Repair whatever you can. If you don't see anything wrong, the short must be in the main body of the harness, which means that you have to replace the harness. For repair or replacement of wiring, refer to (para. 4-85). Replace distribution box, refer to (para. 4-5.1). 6 1 2 3 4 5 Glowplug Controller Harness Schematic 0-45 DC VOLTS STE/ICE-R TEST 89 1. Connect RED clip to the indicated test point, BLACK clip to negative or ground. 2. Start Test 89, DC volts. 3. Displayed reading is in volts. Disconnect negative battery cable before discon- necting and reconnecting distribution box harness. There is battery voltage at the distribution box at all times. Failure to disconnect battery cable will result in damage to equipment or injury to personnel. WARNING NOTE