[Public-list] Why , oh, why won't my glow plugs glow?

[Mpete53 at aol.com]

Randy
 
>From what I have read of your problem it sounds as if you are not getting  
power to the glow plugs or at most to little power. 
 
I find that using a volt meter to check for voltage drops is a handy  
diagnostic tool. A auto ranging digital meter is best but an analog meter will  do.
 
As current passes through your electrical system any resistance will cause  a 
voltage across it. Ideally, the resistance is the item that you want to run,  
IE: lights, pump, Glow plugs. If there is a unwanted resistance IE; a bad  
connection, a failing switch, there will be voltage drops. Since these voltage  
drops are proportional to the current flowing through the wire, all the tests  
must be done while under load. By checking for voltage drops where there 
should  not be one EI: the pos. post of the battery and the terminal on the 
starter  while cranking the engine, you can locate problems. In the example of the  
starter, if there was a voltage reading retry with the test lead on the 
battery  cable clamp not the post. If this time there is no voltage, your problem is 
 between the post and the clamp, dirty battery terminals. 
 
For your problem with the thing you distrust the solenoid. Set meter for  
reading volts DC and find a range that will go as high as 12 Volts. How  place 
your test leads to the terminals on the solenoid red one on the wire  leading 
from the pos. battery terminal and the black one on the terminal leading  to the 
glow plug. (in general, when hooking up the meter leads, the red  test lead 
should be on the section of the circuit closer to the pos.  battery terminal 
and the black lead should be the one further away on the  circuit) 
 
Now the test, when the switch for the glow plugs is off  you should  read 
battery voltage (about 12 volts) when the glow plugs are switched on  you should 
read 0 volts. 
 
If the voltage goes to 0 your problem is not the solenoid. 
 
If the voltage is between 0 and a little less than 12 the solenoid should  be 
bad. 
 
If your voltage does not change, power is not going through the solenoid  BUT 
the solenoid might still be good. There may be a problem in  the circuit 
controlling the solenoid. If this is the case, check the power  activating the 
solenoid. Connect the test leads to the wires leading from  the control switch 
for the glow plugs. If you can find only one wire, most  likely the other 
connection is the case grounding to the block. This time  you are checking a voltage 
across a load on a switch so the voltages we want to  see are reversed. 
Volts switched off 0 OK
Volts switched on 12, feed to solenoid OK so it looks like the solenoid is  
bad.
Volts switched on 11 or less not good. The circuit feeding the solenoid has  
a problem
 
 Good luck
 
Mark

 1127928232.0