I'm attempting to follow the WIS instructions to retrofit the AUX jack (in the glove-box), on my '02 C230K. (I didn't actually buy the cable, yet, because I want to see if this is possible on my car, first.) When I get to the step where I am supposed to connect the 4-pin X39/36 coupling to the white 4-pin plug, I hit a snag. My white plug only has 2 pins, not 4. Plus, there is something connected to it, already. Does anyone have any information on this? I have the Bose system, if that is relevant.