Hi, I believe the yellow connector is for the Airbag system and I think it also acts as the housing for other seating elements like heating and electric seat base.
If you're after the plugs to retrofit heated seats, I have a set of plugs that I removed from a z4 breaker a while back with the intention to make up a wiring harness, but never got round to it unfortunately. Happy to sell on the plugs, will need to dig them out when a get a chance during the week.
