Basic search on this site uses an "and" function, which means that if you put more than one word it looks for hits with all the words. So I searched for "C230 seat relay" and came up with this thread: http://www.peachparts.com/shopforum/showthread.php?t=132934&highlight=c230+seat+relay

I thought there was another thread I posted about it but I can't find it. Long story short you remove the carpet piece from the trunk and there is a relay up toward the rear passenger seat. Just this one relay sitting there. That is the one. You need to either replace it or pry the cover off of it and resolder the pins on the circuit board. If you look at the solder joints with a magnifier you will see circular cracks since it is a single sided board and that is what tends to happen with those. These are the kind of boards you find in throw-away consumer electronincs, and Mercedes.

Mike

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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