My buddy bought a 2004 R53 last week. Drives great and everything else seemed to work other than the brake lights and turn signals. Fuses and bulbs checked. Google search mentioned the BC1. We pulled and inspected it and it looks clean, no corrosion or visible signs of burnt electronics.

We ordered a K+DCAN USB cable and downloaded ISTA-D and ISTA-P. After running ISTA-D the operations report gives about 45 errors, many BC1, but also many others.

Could we just be using this program incorrectly, or could we have a major electrical issue? Taking it to a dealer/mechanic is not an option at this time.

ISTA-D operation report attached.

Any suggestions appreciated!
Thanks!