Hi! I'm new here and I have been searching through all the glow plug indicator issues and have yet to find a problem similar to mine. I hope someone here can help me.

I just got a 76 Euro w123 300d (replaced my 79 240d). When I switch the key to "on" the glow plug indicator lights up but doesn't turn off. I have tried waiting for one full minute and it still doesn't shut itself off.

Since this I cant solve this problem, I just count to 10 and turn the key and the car starts fine and runs smooth and the glow plug indicator light turns off and stays off when the engine is running.

Is there a temperature sensor related to that turns the light off after it reaches the correct starting temp? If so, where can I find it? Or is it a relay wiring problem? Or do I need to change my glow plugs?

Thanks!

There is a temperature sesnor on later models than yours, it is based on coolant temp. If that is bad, your indicator may stay on longer than necessary, but will not effect the way the system glows. A relay controls that and i believe there is one relay for the light, and another for stopping the glow plugs but both are in the same unit.

Not sure where on your car, usually the relay for the GP is on the driver's wheel well in the engine bay.

probably a relay issue.

changing the glowpugs won't change the relay issue unless you start burning up fuses. And if your car is starting without issues, i would not be concerned with them.

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Thanks. The GP relay on my car incidentally is located beside the steering column inside the car, behind the under dash cover panel, not in the engine compartment, (its a big silver thing without a plastic case) unless there is another relay inside the engine compartment?

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1985 300D Turbo
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