REFERENCE INFORMATION Change 1           2-318.5 EXPECTED GLOWPLUG CURRENT ROTARY SWITCH IN RUN POSITION;   GLOWPLUGS ON  : 74 - 125 AMPS 74 is only for weak batteries.  You should get at least 100 amps when glowplugs are working properly.   GLOWPLUGS 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. NORMAL GLOWPLUG OPERATION The glowplugs first come ON when the engine temperature is below 120 °F (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 7-15 seconds then come ON again for about 1 second, then go OFF again.  If you don't start the engine, the glowplugs should keep cycling like this,  due to the glowplug cycle timer in the glowplugs controller.  If you start the engine, they will cycle until the engine is warm, due to the afterglow cycle timer in the glowplug controller.  When the engine gets up to 120 °F (49 °C), the glowplugs should stop cycling completely. ENGINE NOT RUNNING, ROTARY SWITCH IN RUN. If the glowplugs are cycling properly, you should hear a click from the distribution box when the glowplugs turn on and when they turn off. This is the glowplug cycle timer, a thermal circuit breaker.  A good way to check for cycling is STE/ICE-R test 80, battery current.  When the glowplugs turn on, STE/ICE-R will measure 74-125 amps.  When the glowplugs turn off, the STE/ICE-R will measure 3-8 amps. ENGINE RUNNING, ROTARY SWITCH IN RUN If the glowplugs are cycling properly, you can hear a click from the distribution box when the glowplugs 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 STE/ICE-R test 80, battery current.  When the glowplugs turn on, STE/ICE-R will measure 74-125 amps.  When the glowplugs turn off, STE/ICE-R will measure 3-8 amps.  As the engine gets warmer, the glowplugs turn on less frequently and for less time. NOTE If you don't have a STE/ICE-R or a multimeter for measuring current, you can watch the vehicle volts gauge for indication of glowplug operation.  The glowplugs draw so much current that the volts gage should jump about half-an-inch to the left when the glowplugs come on.  Before starting the engine, you should hear the glowplug power relay click open and closed as the glowplugs cycle.  (You can hear the relay after the engine has started by leaning your head under the dash near the distribution box.)  This method won't tell you if all the glowplugs are working properly, but it at least shows that the glowplugs are trying to work and that the glowplug power relay is working. 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 then 30 amps, depending on how many accessories you have on. 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. TM 9-2320-280-20-1