Yesturday I was driving in the rain, wiper on, and as I was pulling into the driveway, I begun hearing this fairly loud and anoying electric static noise comming from the signal switch on the steering columb.

I found that the noise disapears when I activate the signal in either direction or turn on the four-ways.

Today, still occuring, it also came to my attention that on the instrument cluster the following don't work:
* Temperature
* Oil Pressure
* Fuel Level
* & RPM's

I checked the fuses, and all appear intact, has anyone heard of this before? Any ideas? Thanks.

1987 300D Turbo.

Just to add:
This noise happens when the vehicle is running or having the key in run (pre-glow) position.

Have someone check your brake lights - if they're out its probably the combination relay (in the fuse box - the giant one)

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Daily Driver: 02 E430 4MATIC
In the family: '03 E500 // '04 ML500 // 64 220SE

The brake lights do not work. I discovered that the electric static noise is comming from the "Combination Relay", it the the 2nd largest there. The largest one is the "Exterior Lamp Failure Monitoring Unit". I exchanged the "Combination Relay" with the identical working one from my 1990 300D, and still get the same problem, while the one from the 87 works fine in the 90.

After touching the Relays, I discovered that Relay "A" as per electrical drawing, which is the "Power Seat Relay" was soooo hot to touch that I could not even touch it for 1 sec.

I am waiting for it to cool, and then I will pull it out and swap it. I don't think it is normal for a relay to heat up so much???

I can't figure it out, All relays, when switched with functioning ones don't help the problem.

Also to add: When going through the pre-grow process, the following lights do not light up on the cluster as they use to:
*Parking Brake
*Brake Wear
*Oil Level
*Coolant Level
*Washer Fluid Level
*Ext. Lamp Notification

Also when the vehicle is running, and I open the drivers door, the buzzer inside starts beeping as if I left my keys in the ingnition or the lights on. Normally it would do this when the car is off.

ANY ideas on what to check, sensors, switches??? It would be greatly apprechiated.

Sorry for bumping a thread from over ten years ago, but I am experiencing the same problem with my Benz. It has got all of the same symptoms. Would anyone happen to have a fix for this problem, as one has not been described in the above posts?

Thanks!

Usually odd behavior like this is caused by a ground that has lost conductivity and the circuit tries to find a ground through unenergized circuits. MB tends to place a pile of grounds on a common bolt / terminal strip resulting in many circuits becoming affected.

You could PM the OP.

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1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra