<FONT face="Arial, Helvetica, sans-serif" color=blue size=2>We have a '78 240D. (Mileage unknown; odometer broken) About half the time, the glow plugs don't activate when we get ready to start up. Occasionally, the glow plugs will kick on while we are driving.</FONT></P>


<FONT face=Arial color=#0000ff size=2>Where do I begin my investigation? I've already made certain that obvious connections are clean and tight. I don't want to wear out the starter with continuing cold-cranking starts! </FONT></P>


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The pre-glow relay strikes me as a likely suspect...

 

<FONT face="Arial, Helvetica, sans-serif" color=blue size=2>Thanks Ron. I am assuming there should be continuity through the relay when cold.(Isolated from circuit) And, that there should be 12 VDC "out" when cold with ignition switch in "on" position? AND, that if one, or both of these things do not happen, I should spend money? </FONT>