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Looking for anyone who could advise on the Rear SAM connection for the heated cooled cupholder I have retrofitted from a W166. I have all but one wire connected which I cannot confirm it’s termination or function. I found a schematic that shows connecting to term 47 in Rear SAM but the C292 has a wire in this terminal And am not sure if I should join to it or if it’s the correct schematic. I have read the 2017 had heated cooled cupholder but the 2019 I have did not.
Really could use some help on this one with maybe a wiring diagram or schematic. Thank in advance.

ps 12v + & - connected and interior illumination it would seem the 4th wire is a signal wire?