Can someone please tell me about my glow-plug indicator light not coming on? I have a 1981 300SD turbo-diesel and this light just yesterday stopped coming on during the warm up phase. We leave the ignition key in the warm up phase for the usual time it takes and it seems to start just fine. In recent years when this light didn't come on, the engine started alright for awhile but eventually it barely started and later we found out that one or two glow plugs were not working. For today's symptoms our mechanic suggested we wait for additional symptoms because he didn't feel like he'd find anything. While he might not be a Mercedes or diesel expert he is our trusted mechanic and in the past we believe he has competently handled repairs including past glow plug work. Is there anything I could or should get checked before I get stuck somewhere? Thank you very much for any help you might be able to give me! yours, Peter

Depending on how warm it is where you are, the first symtoms could be no starting. I think the light out usually means you have a bad glowplug. They can be tested to determine if they have the proper resistance I think? Hopefully someone who knows more will chime in.

Does it take longer to start? If I don't glow mine it cranks a little longer before it fires.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

When the glow plug light doesn't come on or lights up after the engine has started then it's an indication that a glow plug has failed. it will probably beonly 1 or 2 but if you fix them now then you won't get stuck somewhere with a car that won't start

Check the resistance of each glow plug when the engine is COLD (pull off the plug from the glow plug relay) and any plug with more than a few ohms resistance should be replaced.

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Alex.

MB Tech
Sydney, Australia
Volvo 122S
W201 190D 2.5 manual
W202 C240
W203 C32

also if you look a your dome light it should dim if things are working ... i'm kind of gessing because mine are sereis