When I turn the ignition on my '83 MB 300D the glowplug light always comes on. No problems starting even in cold weather.

Last spring when it started getting warm the glowplug light on my '85 MB 300TD stopped lighting up. I assumed it was at least one bad glowplug. I forgot about it until now (when its cold). I assumed I'd have to replace glowplugs but to my surprise the glowplug light is now working again. No trouble starting even in cold weather.

Seems on the '85 300TD the glowplug light only comes on when its cold enough to need it.

So do the glowplugs lights on a '83 300D and a '85 300TD really work differently? How are they different?

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JWJ
1983 MB 300D - > 430,000 miles - Deep Blue - Bilstein Comforts - 0-60 in 24 seconds - 27MPG
1985 MB 300TD (wagon) - > 275,000 miles - Manila Beige - Thule rack - 0-60 in 18 seconds - 22 - 25MPG
Biodiesel, Mobil Delvac 1, and Viton fuel lines!