R129 Help: Nothing electrical works!!!

[tamango]

Well, not everything, but almost everything. I own a euro 94' 280 sl (I live in Spain) and the problem began about a year ago.
First I noticed that the lighter of the ashtray did not work, then the wipers and wiper washer, electrical seats, heating of the seats (the lights in the switch flashed when I pushed it, but now it does nothing), hazzard warning lights, turn signals, flashing high beam (but high beams work), abs light on (and abs does not work, verified) some time later electrical soft top wont go down ( but it makes the right noises when I force it up), and now fifth gear fails to stick in (it is electrical -automatic transmission).
Apart from all this, the car works flawless, starts inmediately, no dimming lights, stereo works fine, dashboard ok too, interior and exterior lights ok (except turn signals), good power and normal fuel consumption.
What is happening? I resist myself to take to the AD because the may charge me like a new car "finding" the trouble, following some thread on this forum about six months ago I changed the combination relay, without any success, all fuses seems to be OK, no rust, and also the battery.
In a spanish forum I've read a similar problem in a w124,the computer at the AD found nothing, and they finally discovered there was a bad module somewhere in the car (in that case at the drivers door), they claimed that these modules work linked and when one fails it makes others fail too, other people tell me it can be a bad ground contact,
I write here hoping this is a more or less common problem and you know what exactly can cause this, any advice or clue will be very apreciated.

please forgive my terrible english,

regards from Spain
Javier

[RKreutzer]

Hi there,
my guess would also be poor ground connection. I used to pull a motorcycle trailer and after two years the plug was so corroded that electricity would not flow anymore. Had to clean it every year.
Are you near the ocean? Salty air can lead to faster corrosion.
I would look at the ground connections and see how they look.
Scrape clean and use dielectric grease to prevent corrosion in the future.
Good luck