I have a 1980 w116 300SD that has all of a sudden developed a weird symptom; the RPM, FUEL, and COOLANT-temperature gauges just stopped working, the oil pressure gauge DOES work and so does the clock and cluster lights..... also when I open the drivers door while the car is turned on the signal buzzer goes on, it only did that before when the car was turned off and the key stuck in the ignition while the door was open(which is the normal I believe).... This happend at the same time the speedo started acting out. Any ideas what could be wrong? I checked the fuses already and all OK Thanks!

It's possible you have a loose ground on the cluster as the Tach, Fuel and Coolant gauges are all electrical. Off the top of my head I don't recall if those gauges are fused but you can easily check that.

The oil pressure gauge is mechanical so it won't be affected by electrical gremlins. Same goes for your speedometer, it's cable driven from the tranny, so just coincidental with your gauge issues.

__________________
Joe

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1980 300SD - 495k miles - 'The Ambassador'
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Former Family Members
95 C280
73 280SEL
90 300D
87 300SDL (X2)
86 560SEL
84 300D
80 300SD

You could have a problem with the ignition switch or wiring. Do your warning lights (idiot lights?) come on when starting? Your symptoms sound like the switch is not sending the signal that the ignition is running.

I just checked and it seems that the turn signals dont work either, and I mean when i pull the lever up or down no green blinker signal at the dashboard BUT if I press the red hazard button they do start flashing even the green arrow blinkers at the dash, now that if twist to engage the wiper blades they do work, so it cant be the lever. Its weird this all happen at the same time so it must be something somewhere causing all this?

Doublecheck the push on connector on the back of the instrument cluster. Rarely it works it's way loose.

__________________
Codifex
1981 240D ChinaBlue (Got her running with a donor engine.)
1983 300DTurbo w/sunroof.
1984 300TD manual sunroof. (Electrical Gremlins)

Thanks for the suggestions, I will check the cluster connections tomorrow when sun shining. One more thing I forgot to mention is that it seems all this happened 3 days ago when my front-left wheel bearings crapped out after being installed by a supposed "expert" mechanic only 4 days before. I pulled off the freeway to hear this scary sound that seemed like my tire was about to come off, so I stopped completely, got off and saw grease dribing from the wheel cap. I then went back inside the car and started driving again real slow but that grinding-loose noise was present, and when I braked it felt like I had to push all the way down, lucky for me my workplace was only 2 minutes away, so I had the car towed home. Afterwards I noticed all this mysterious cluster symptoms when I started the car again.

had a similar prob in my 85 300D and if yours uses the same fuses (and mine were alum) i'd check that first, they can look completely normal

spun the fuses one at a time and when I got to the right one my gauges and windows worked again

pitting/corrosion (oxidation??) at the fuse-box even if only one fuse is affected can wreak havoc

good idea to keep that fuse-box in tip top shape, cleaned it all up (the contact points) with light sandpaper and a wire brush, suppose dielectric grease wouldn't hurt

Hey thanks for all your suggestions. It turns out it was the #4 fuse that was bad even though it looked perfectly fine to the naked eye.

Holy smokes....I installed a new white fuse and it burned out when I started the car....short somewhere ..this is fantastic just what I needed

i'd try another might be the fuse was bad