I've seen this diagram, but it only gives instructions for the E53s with nav and those with Business CD, which I have neither. I have the X13598 harness, while the diagram only shows directions for X18126 and X14118. If you go further down the pdf, you'll see the circuit diagram for X13598 and you'll see what I'm talking about how slots 3,4, and 10 are the ones I need to put the aux wires in, but slots 3 and 4 are already used.