TM-9-2320-280-20 HMMWV Technical Manual Unit Maintenance Volume 1 Download
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TM 9-2320-280-20-1 REFERENCE INFORMATION Change 1 2-318.3 If the engine cranks ok (or starts), then the batteries are good enough for testing the glowplugs. If the engine starts, shut it off. You can use STE/ICE Test 10 to measure cranking speed. The engine should crank at least 100 RPM in cold weather and at least 180 RPM in warm weather. BAD CONNECTIONS ARE THE MOST COMMON PROBLEM ! Sometimes, just disconnecting, cleaning and reconnecting will solve a problem. BE THOROUGH ! The time you save may be your own. Refer to the functional flow schematic and check the following; 1. BATTERY - make sure all connections are clean and tight, including the shunt and power stud. 2. DISTRIBUTION BOX - unscrew the three connectors and look for bent or broken pins, pins pushed out of their socket, or dirt and corrosion in the connections. 3. GLOWPLUGS - Check that all the glowplug wires are snug. Don't just look with your eyes. Many problems are solved by looking with your fingers to be sure a connection is snug. NORMAL GLOWPLUG OPERATION The glowplugs are heated quickly for 5 to 20 seconds. This cycle is active while the "Wait-to-Start" light is on. The length of "on" time is dependent on battery voltage, the weaker the batteries the longer the "on" time. This cycle will only repeat if the run start switch has been off for more than 2 1/2 minutes. After the initial 5 to 20 seconds preglow, the system goes to afterglow. Afterglow provides lower voltage to the glowplugs to keep them at operating temperature for approximately 60 seconds. To check for glowplug current draw, start STE/ICE-R Test 80, battery current. Turn off all accessories (lights, heater, wipers etc). STE/ICE-R should immediately measure at least 74 amps. Take note, however, that if all your glowplugs are working, the current draw should be close to or more than 100 amps, especially if it's cold. If it's near freezing and the glowplugs only draw 75-80 amps, you probably have a few bad glowplugs. GLOWPLUGS 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. NOTE The “WAIT-TO-START” lamp is NOT diagnosed in this section. If the lamp does not work properly, the glowplug circuit may be affecting its operation. Run these tests to check out the glowplug circuit. If the lamp still does not work properly, go to the INSTRUMENTS section for a full diagnosis of the lamp's problem. 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. Disconnect negative battery cable before disconnecting 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