I have 2 420 SEL Mercedes. They are a 1987 and a 1988. They both have a short somewhere that I cannot locate. The short blows the fuse that controls the central locks and power antenna. I have no idea where the short is but it seems like it might be a common problem. The fuse blows immediately when I replace it.

Odd coincidence, both 420's at once... Sure you're using the proper amperage rated fuses? (Sorry if this is too obvious, but it would explain the common problem in the cars.)

Anyway, assuming you're using the correct fuses, I'd start by disconnecting one of the antennae in the trunk. See if this does the trick. If so, you've localized your problem. If not, you'll have to methodically test each device on the circuit until you track down the short. Check the card in the fusebox to find out what's on your checklist...

Good luck!

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Eric

1991 560SEL-Euro (214,000 miles)
1989 420SEL (Retired from daily use at 325,000 miles; Use as donor vehicle)

. . . not long before my 420SEL was totaled. I think I remember the power antenna being involved -- I'd turn on the radio and the antenna wouldn't go up, and the central locking wouldn't work. The fuse for the central locks kept blowing out, even though I replaced it twice.

Turned out the central locking pump had failed. I disconnected it, put in a new fuse, and everything was fine, except that I couldn't lock the car with just one key turn; I had to lock the doors and trunk separately.

The pump in mine was in the spare tire wheel well. I've also heard that in some models of W126, the pump is located under the rear seat.

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-- Paul W. (The Benzadmiral)
('03 Buick Park Avenue, charcoal/cream)
Formerly:
'97 C230, smoke silver/parchment; '86 420SEL, anthracite/light grey; '84 280CE (W123), dark blue/palomino