Ok, I have a crazy issue going on with the instrument cluster. Anytime I engage the turn signal (either left or right) the guages on the instrument cluster go whacko and a bunch of warning lights come on for about a second. This only happens when I either engage the turn signal left or right.
Some techs have told me the instrument cluster has to be changed ($800) and some other techs who have seen the car have said they just don't know what it is. I am hesitant for now to change out the cluster and blow $800.

The car runs absolutely fine, only when I engage the left or right turn signal it seems the instrument cluster just goes all whacko for about 1 second like its been possessed and returns to normal

any ideas? Thanks

It is a very common issue on the pre 94/5 cars. the voltage regulator in the cluster becomes unstable. there have been some who replaced the regulator capacitor with sucess, it requires the removal and soldering on the cluster. There are others who claim it could be a bad ground, bad regulator in the alternator. It happens to trigger with the windshield wiper, turn signal, and lately when my wife turns on the mirror lamp in the visor.
Then there is MB who was swapping out clusters and selling a new "board" during and post warranty for the digital odometer version. Mercedes is selling a new cluster for $ 1,000, coded to your mileage there are some who are rebuilding them.
This company describes the symptoms and repairs clusters but in Canada
http://mbcluster.com/
This is a US location
http://www.bba-reman.com/catalogue/DetailedProduct.aspx?DetailedProduct=393

benz world members forum
http://www.benzworld.org/forums/search.php?searchid=3623239
various members input including mine

No doubt this is caused by a dried-up capacitor in the voltage regulator circuit in the cluster main board. It is easily replaced, and countless people have done the repair. This thread shows the location of the capacitor on the cluster of an R129 SL: '94 SL500 instrument panel gone nuts.

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For Sale: many used R129 parts from a white '92, black interior. Send email if interested.

thanks for that info BobTerry..

Now, where can I get one of these capacitors? At a local Radio Shack or do I have to go to the dealer? Also, how much do they generally cost? I'm going to try this first before I do anything. Again, thanks for your help.

You can get a capacitor at Radio Shack. Cost will be less than $2.

__________________
For Sale: many used R129 parts from a white '92, black interior. Send email if interested.

I hope you have experince working with printed circuits, like a solder sucker, low wattage soldering iron, and have the dash removal tools. The Benz world link also has photos...

Ok great. Thank you all.

BobTerry: What size Capacitor do i need? volts/watts? And how many are there total to swap?

Peter: I have the pulling hooks to get the cluster out. Piece of cake, I can get the cluster out in less than 3 min.

I haven't used a soldering iron in awhile, but will pick one up at my local HomeDepot/Lowe's and atleast attempt to change these capacitors. Can't hurt, can it?

I am going to attempt this repair on my W140.

Is the circuit board subject to getting zapped by static electricity like a computer circuit board would be? How careful should I be with it?

Thanks to all posters for the great information.

Harry

Ok, so I attempted this fix today and swapped out the capacitor. Plugged back the instrument cluster in and now the fuel guage, speedometer and oil guage does not work!!

Basically, the only thing that works are the turn signals. Not sure what to do now? I am thinking about using MBCluster.com and sending it to them for this fix.

The capacitor was only $1.29 at Radio Shack (470 UF at 35 volts) and the Soldering set was only $8.99.

Help

By no means I'm an expert but I had the same issue with my instrument cluster and was able to fix it myself.

One thing I can think of is the polarity of the capacitor. Did you note the polarity of the original cap before replacing it?

Hi Chedeng,

The original capacitor was 470uf 16V. The one I replaced it with from Radio Shack was 470uf 35v. Could this be causing the problem? Looking at them physically, the stock capacitor is slightly larger in physical size than the replacement.

I see you're in Rockland County as well -- we're neighbors

Thanks,
Agron

Agron,

I replaced mine using the same capacitor which was also from Radio Shack 470uf 35v so it should have worked fine. Unless something has happened while you were working on it like static electricity zapping other components then it might not be easily corrected. I will let others chime in.

I sent you a pm also.

thx
chedeng

I don't think so. But maybe Agron's board was zapped with ESD. May as well ground yourself with a bare wire wrapped around you wrist or finger.

__________________
For Sale: many used R129 parts from a white '92, black interior. Send email if interested.

It seems I am simply going to leave this up to the professionals as I do not want to continue tampering the the cluster. I did, however, have a question about replacing the cluster with a another one from a newer model W140 (95-99) which has the digital odometer reading. Considering that the connectors were the same, would a cluster with a digital odometer reading work in a 1992 300SE (which, of course has an analog odometer reader). There are an abundance of 140 clusters on ebay selling for relatively cheap.
Was toying with the idea of possibly swapping out the entire cluster from another vehicle.

thoughts?

From what I have seen and been told, the 94 cluster is a direct replacement. it has to be a 140 not a 129 they look identical. Of course changing the odometer to the correct # is an issue when selling the car. It is a US federal law violation as to disclosure of true mileage. As someone stated previously, did you install the capacitor properly or break the foil, PC soldering requires skill.
I have not seen an abundance of 140 clusters, when I looked