One stupid power wire..

[stender_e30]

I'm swapping a 94 vanos M50 into a '90 325i. Have the harness connector wired, working on power wires currently. The two opposite ends of the wires (pictured) connect to the terminal block on the passenger side, I know that the thicker wire on the left connects to the larger terminal on the starter solenoid. As for the wire (black cover) on the right, where does it connect on the driver side? Starter?

Don't like asking questions about this swap since 99% of them have been answered many times over but for the life of me, I cannot find anything. Thanks for the guidance.

[duval7]

I am not a 100% but I think it goes to the back of the alternator. I know a large wire goes from alternator to starter so i beleive that is what you have.