I had a relay that worked but did not power the light. I swapped the bulbs around to find out, but didn't figure out the wire color. Since you have a spare relay now, open the little guy up. You can clean the contacts and it will probably work if nothing is burned up. If nothing else, it's fun to see how it works.

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1979 240D Caledonia Green/cream gone
1982 240D stick Ivory/Palimino
1999 E300D White/grey