Quote:
Originally Posted by Brian Carlton
Jim, his test was valid. He measured voltage directly at the glow plug tip and found zero.
All the resistance checks in the world are meaningless if there is no voltage at the plugs. I wouldn't bother wasting time on them.
Naturally, I'm presuming that the plug was inserted in the relay end.
If the fuse has not been replaced in the glow plug relay...........now is the time to do so.
Additionally, it's time to see if there is voltage at the relay. See if you get 12V at one...........or both..........screw terminals that hold the fuse in place.
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I apologize. I misunderstood his test, but still don't find it definitive. if you measure the voltage from the tip of the connector to ground with the key in the #2 position you have to be sure the time on the relay has not expired and you have to be sure the relay actually has power. And, at that point about all the test would prove is the wire from the relay to the plug was broken.
Checking the health of the glow plugs is typically done by measuring resistance. Checking the health of the circuit, including the relay, is typically done by looking for voltage when the relay is supposed to be sending the plug power. If the relay has voltage, and the glow plug doesn't either the switching element in the relay is kaput, or the wire from the relay to the plug is shot, or, as has happened to me, the connector plug was left unplugged at the relay and then you get squat to all the plugs. I have done this twice - left the plug off - and it is immediately obvious. I had some plugs working and now none. But it is still irritating.
So, I thought we were investigating the health of the plugs he has installed. I still maintain RESISTANCE is the measure of glow plug health.
When looking for voltage at the fuse, you again need to make sure you turn the key to position #2 within a minute or so of when you take those voltage measurements. Jim
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Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles
Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)
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