TM-9-2320-387-24 HMMWV Direct Support & General Support Maintenance Manual Volume 1 Download
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REFERENCE INFORMATION I NoRMALGLoWP- 1 The glow plugs first come ON when the engine temperature is below 120 OF (49 “C) and the rotary switch is turned to RUN. They stay ON for up to 9 seconds and then go OFF. They will stay OFF for about 7-l 5 seconds then come ON again for about 1 second, then go OFF again. If you don’t start the engine, the glow plugs should keep cycling like this, due to the glow plug cycle timer in the glow plugs controller. If you start the engine, they will cycle until the engine is warm, due to the afterglow cycle timer in the glow plug controller. When the engine gets up to 120°F (49°C) the glow plugs should stop cyckng completely. If the glow plugs are cycling properly, you should hear a click from the PCB when the glow plugs turn on and when they turn off. This is the glow plug cycle timer, a thermal circuit breaker. A good way to check for cycling is STE/ICE-R test 80, Battery Current. When the glow plugs turn on, STE/lCE-R will measure 74-125 amps. When the glow plugs turn off, the STEIICE-R will measure 3-8 amps. FNGINF RUNNING. ROTARY SWITCH IN RUN If the glow plugs are cycling property, you can hear a click from the PCB when the glow plugs turn on and when they turn off (you may have to duck your head under the dash). This is the afterglow cycle timer, a thermal circuit breaker. A good way to check for cycling is STEIICE-R test 80, Battery Current. When the glow plugs turn on, STEIlCE-R will measure 74-125 amps. When the glow plugs turn off, STE/ICE-R will measure 3-8 amps. As the engine gets warmer, the glow plugs turn on less frequently and for less time. NOTE If you don’t have a STEACE-R or a multimeter for measuring current, you can watch the vehicle volts gauge for indication of glow plug operation. The glow plugs draw so much current that the volts gauge should jump about half-an-inch to the left when the glow plugs come on. Before starting the engine, you should hear the glow plug power relay click open and closed as the glow plugs cycle. (You can hear the relay after the engine has started by leaning your head under the dash near the PCB.) This method won’t tell you if all the glow plugs are working property, but it at least shows that the glow plugs are trying to work and that the glow plug power relay is working. TM 9-2320-387-24-l GLOW PLUGS CIRCUIT I EXPECTED GLOW PLUG CURRENT ROTARY SWITCH IN RUN POSITION: GLOW PLUGS ON: 74 - 125 AMPS 74 is only for weak batteries. You should get at least 100 amps when glow plugs are working property. GLOW PLUGS OFF: AT or NEAR ZERO With the rotary switch in the RUN position, other parts of the vehicle are drawing current. You might measure up to 8 amps. I BATTERY CURRENT STMCE-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. I BATTERY CURRENT MULTIMETER I 1. Set the voltmeter to a DC volts scale of about 1 I 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 = 1,ooO amps. To get current, multiply millivolts x 10. 2-293