Here's a post that talks about the installation on a W126:

Mein E-code lights are in!!!!

You don't need extra wiring or anything if you use the standard bulbs.

Mike Tangas talks about soldering a wire in, but that's only for the city lights set-up, which most people don't do. Here in the U.S. we don't have city lights.

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Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".