More info on the mystery wire on a 68 250SE

I am in the final stages of restoring a 68 250SE, 108.014. I have a wire that I am not sure where it connects. In an earlier post, I indicated that the wire was conneted to the voltage regulator. It now appears that this may be the fuel pump relay (?)not the regulator. Writing on the label I affixed to the wire has long since faded. The wire is green with a black tracer. One end is terminated to pin 4 on the relay the other end is terminated with a ring lug. I cannot find any reference to this wire or relay in the Mercedes 108 shop manual either vol 1 for cars up to 67 and vol 2 68 and up. I am thinking it was on the + of the coil. Any info would be much appreciated.

[Benzmac]

I am printing this off so I can ask the old timer I work with. He is a Miester from the mother land.

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Benzmac:
ASE CERTIFIED MASTER AUTO TECHNICIAN
LEAD TECHNICIAN FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM