The windows and sunroof died on my W124 1990 300D 2.5T. I traced the problem down to a faulty convenience relay module in the engine compartment fuse/relay box. Dealer price is about $65! Given that I'm cheap, but refuse infect my cars with Uro crap, I decide to take a stab at repairing it. The part is also used on several other models, such as the second generation 126s.

Examination showed the soldier joints had cracked. Not surprising after having been shaken by a OM602 for over 210K miles. The cracks looked very much like those in troubled cruise control modules. Accordingly, I should be repair them just the same.

Using a 20-25 watt soldering iron, I touched each connection until the existing soldier bubbled hot. I then added a wee bit more soldier to make up for that which crumbled away. I replaced the cover, plugged it back in and I now have working windows and sunroof.

Here are some before and after pictures.

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http://i284.photobucket.com/albums/l...aman/Fleet.jpg

Peach Parts W124.128 User Group.

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85 300SD
87 300TD
92 300D 2.5 Turbo
92 300TE 4Matic