w124 easy glow plug testing

300TDT

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E300 W124 diesel estate 1996, E300 W124 turbodiesel estate 1994, Golf tdi convertible,
My glow plug lamp has been coming on intermittently for a few minutes after start up.

I replaced the glow plugs last year - but thought I'd better check them with winter approaching. I normally do this by putting one probe of an ohmeter (ie a multimeter set to resistance) on the end of each glow plug and the other probe to the car body. In my experience there either is low resistance in which case that plug is OK - or it's open circuit and duff.

It's a difficult job on my car though, the inlet manifold from the turbo makes access very difficult, and then the reading is less than certain.

For the first time it occurred to me that if I pull the electrical plug from the glow plug control unit mounted on the inner wing - which is connected to each of the glow plugs - I could easily test each glow plug by simply probing each pin. The whole job took 5 mins.

Perhaps everyone else is aware of this tip and think I'm daft not to have thought of it before - but it might help someone.
 

television

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2002 SL500, 216 CL500, all fully loaded
Nice to know and we do not all think of the obvious all the time:D:D
 

Number_Cruncher

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1995 W124 E300D TE
>>if I pull the electrical plug from the glow plug control unit mounted on the inner wing

It's one of the hidden nice features of MB diesels. Cheaper makes of car tend to use a bus bar which means you have to do some serious dismantling to electrically seperate the glow plugs for testing.
 

simon_wall69

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My glow plug lamp has been coming on intermittently for a few minutes after start up.

I replaced the glow plugs last year - but thought I'd better check them with winter approaching. I normally do this by putting one probe of an ohmeter (ie a multimeter set to resistance) on the end of each glow plug and the other probe to the car body. In my experience there either is low resistance in which case that plug is OK - or it's open circuit and duff.

It's a difficult job on my car though, the inlet manifold from the turbo makes access very difficult, and then the reading is less than certain.

For the first time it occurred to me that if I pull the electrical plug from the glow plug control unit mounted on the inner wing - which is connected to each of the glow plugs - I could easily test each glow plug by simply probing each pin. The whole job took 5 mins.

Perhaps everyone else is aware of this tip and think I'm daft not to have thought of it before - but it might help someone.

Sound advice, makes sense. Those inlet manifolds are pigs to get off on NA ones as well.
 

swannymere

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S124 1994 E300D
Obvious when you think about it, thanks for the tip!
 

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