TM 9-2320-280-20-1 REFERENCE INFORMATION         Change 1           2-311 Ensure that alternator "AC" tap is functioning correctly by measuring DC volts at wire 2A. Reading should be between 9-16 Vdc. If this votage is not present, glowplug system will never stop cycling. Refer to the functional flow schematic.  If the glow- plug controller 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 glowplug controller connected, there must be a short in the harness or a stuck relay in the protective control box (PCB). 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 glowplug controller 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 than 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 protective control 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 PCB, refer to (para. 4-5). 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 protective control box. There is battery voltage at the PCB at all times.  Failure to disconnect battery cable will result in damage to equipment or injury to personnel. WARNING NOTE