Recently, some gauges stopped working on my 1990 300E. The tach, water temp, gas, and oil pressure gauges suddenly quit, although the car still runs fine. Coincidence or not, a buzzing noise started coming from one of the relays near the fuse box at the same time. The relay (M-B part No. 201-821-00-47) is supposed to be for the lighting. The lights operate as they should. Does anyone have an idea what could have caused my gauges to suddenly stop working? It was a pretty hot day in Central Texas, I had just stopped to put gas, and the temp was running just above 100C. Thanks for any input or ideas...

hello rolls88,

check ALL of your fuses. the same thing happened to me earlier this year.

it's definetly a fuse.if you don't have any extras at the moment,use your fog light fuse until you can get more.

thank GOD for mercedesshop.

peter

It is most likely a white fuse, probably #5 (on my 87, your 90 may be different, look for a fuse that controls the instruments:

http://www.warewolf.net/jelliott/fuse.jpg

The fuse develops a hairline crack, and makes rapid intermittent contact, causing the buzzing component. I learned this little tidbit here from these great folks 2 years ago when mine did the same thing. This fuse also controls your brake lights, which may not be working either, depending on how rapidly the fuse is cycling on and off. Even if the fuse looks good, replace it. Regards,

Thanks for the help. It was definitely #5. The fuse appeared to be perfect, until I touched it. That's when it fell apart. Now, everything is back to normal. I ended up replacing all the fuses since they were mostly originals. Thanks again for the advice, I *really* appreciate it.

I had the same symptom coming to work this morning - gauges quit and I could hear a faint buzzing sound. Kind of resembles the sickly sound of the worn-out key in ignition buzzer in my Miata beater/autocross car.

So as soon as I got inside work, I checked the forum and found this post. I never expected to find an EXACT duiplicate of my issue.

Replaced #5 fuse and all is well.

THIS FORUM ROCKS!:D

replace them all, it is not very expensive and well worth it.

yes, m.b.shop rocks indeed.


peter

#9 fuse for 190e
 

Same issue today on my 1991 190e. Temp, fuel and oil pressure gauges inop. Fuses all looked OK but #9 was open circuit.
Turns out that I also drove home with inop brake lights!
The fog light fuse is being used until I can get a spare. :)

Add Fuse #5 for a 1991 300 CE to the list...

I want to thank all of you guys for your posts, I was sweetng bullets, till I found this thread on the web....

Rock On Dudes

http://aptient.com/images/billted.jpg

Buzzing under hood in fuse box
 

My 1995 E302 died and when I turned the key all I heard was a buzzing coming from the fuse box. I researched your site found the recommendations to check the number 5 fuse and bingo. The fuse had a hairline crack I didn't notice until I removed the fuse. Thanks guys, you saved me some $$$$