I just replaced my plugs, so I’m confident it’s not them. The passenger seat belt warning light has flickered on and off since I bought the car, but now, and ALWAYS at the exact same times, the glow plug dash light also flickers on and off. The plug light also doesn’t turn on or stay lit anymore when starting/cycling the plugs.

I had the cluster loose the other day, might a ground or something haven shaken loose? Any pics or tips?! Thanks!


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Whether this is your exact issue or not, I don't know, but at one time with my '81 300D, I'd have occasional instrument panel (gauge) flicker. One time, the entire panel went stone dead for a few minutes! Saw the fix below online, and since performing it, have not had any issues whatsoever with any gauges or dash lights. Fair warning; there are wires and cables going all over hell's half acre once you are able to access the instrument panel, but I'm assuming you already know that since you've had the cluster loose. Again, your issue doesn't sound quite exactly the same as mine, but to me, it's worth a shot. YMMV.

Mercedes 300D 240D w123 Gauge Cluster Short DIY Fix | Up-Fixin | The Motoring Journal

Yeah, the idiot lights in our '81 240D light up at random especially the seat belt light. The Tech says I can have him chase down the cause or I can just live with it since there's nothing wrong with the car. The lights all work properly when needed, they just have a mind of their own.

I choose to live with it.

The lights really come on if I'm winding the piss out of it.

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1981 240D Four on the floor, Orient Red over Parchment, bought with 154,000 but it's a daily driver and up to 180,000 miles, mostly original paint and all original interior.

It’s funny you mention that - I’d say I had no problems with the glow light the first 500 miles I owned it....then flicker with passenger seatbelt light for maybe 300 miles, but then back to normal working order....then the last couple months the glow light has been flickering just like the passenger seat belt light


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If the seatbelt buzzer starts sounding randomly I’ll have it fixed. The dash lighting up like a Christmas tree I can live with.

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1981 240D Four on the floor, Orient Red over Parchment, bought with 154,000 but it's a daily driver and up to 180,000 miles, mostly original paint and all original interior.

Awesome, thanks! I’ll try it this week and report back!


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So the big silver relay under the outside driver’s footwell has the buzzer built into it - but mine has never buzzed with the seatbelt, just if lights on/door open while key in ignition. I guess I assumed the seatbelt light on the passenger side is the passenger seatbelt light but I guess maybe it’s the driver belt signal?!


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