S124- front windows blowing fuse

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chilsta

Active Member
Joined
Jul 18, 2010
Messages
105
Car
'94 S124 E300D
This started yesterday. Bit of sunshine down here on the south coast, so pressed both front windows down to the 2nd position so they auto-roll all the way down. When we came to do them up they weren't moving- replaced the blown fuse and they went up OK.
Today I had the same problem again, so I thought I'd try one at a time- figuring it was a motor or other issue in one of the doors. Each time the same fuse blew. If I don't get to the 2nd position on the switch all seems to be fine. So it's something common to both doors, that's only happening when the windows get all the way down on auto-wind-down. I'm guessing a relay, but could do with a 2nd opinion before splashing out. Is it under the rear seat on an estate- opposite side from vacuum pump?

Recently replaced all fuses with new ones (precautionary measure as some were looking a bit corroded, have had nothing else strange happening).
Back windows are on a separate fuse and seem unaffected.

Any ideas?

Thanks
 
Did you replace with brass fuses or the cheap eBay ones? Did you keep the old ones? Pop one back in and try. It could be a duff switch.

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When I have a similar problem with my old 190E it turned out to be one of the window switches causing it. I would suggest that you get a good switch and swap with one of the current ones and see if it cures it.
If not swap out the other and try it, worked for me.
 
Did you replace with brass fuses or the cheap eBay ones? Did you keep the old ones? Pop one back in and try. It could be a duff switch.
They were cheap ebay ones- picture showed them as brass but silver ones turned up. Do you suspect the blue ones might not be allowing the current through that they should?
Do you have a source of decent brass ones?

When I have a similar problem with my old 190E it turned out to be one of the window switches causing it. I would suggest that you get a good switch and swap with one of the current ones and see if it cures it.
If not swap out the other and try it, worked for me.
Interesting- I did have the wooden panel and plastic switch caddy apart recently while working on some unrelated wiring. Maybe I disturbed something. I'll check the switches and try disconnecting one at a time.

Thanks a lot for the help.
 
chilsta said:
They were cheap ebay ones- picture showed them as brass but silver ones turned up. Do you suspect the blue ones might not be allowing the current through that they should? Do you have a source of decent brass ones? Interesting- I did have the wooden panel and plastic switch caddy apart recently while working on some unrelated wiring. Maybe I disturbed something. I'll check the switches and try disconnecting one at a time. Thanks a lot for the help.

You can still get the correct brass ones on eBay. Or try Mercedes direct. As mentioned the switches can be a known weak point try swapping with one that is not blowing. Still worth trying one if your old fuses if you have them.

Sent from my iPhone using MBClub UK
 
We've had something similar on one of our R129's... lubricated the window regulator, and hey presto, no more blown fuses. Not sure if it will be the same case on your S124, but it's a good reminder to keep the mechanism greased...!
 
Thanks go to brucemillar -
I did keep the old fuses (and people try to tell me that holding on to old crap is stupid)- tried one of those and no issues since.
Will be buying another set of fuses, this time I won't mess around and get them straight from MB.
 
Oh yes, thanks to Lxb3 for the suggestion too- I had greased all the door internals earlier in the year and they seem to be moving well so I was fairly sure that wasn't the problem, but good call- could well have been that.
 
Thanks go to brucemillar -
I did keep the old fuses (and people try to tell me that holding on to old crap is stupid)- tried one of those and no issues since.
Will be buying another set of fuses, this time I won't mess around and get them straight from MB.

I had this problem with some fuses from Halfords a couple of yrs ago.

I've since heard that a faulty Chinese batch had entered the UK supply chain, not sure if true or not.:dk:

I replaced with some sourced from ebay or Amazon and not had a problem since.
 

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