My GOD, I never ever want to go through that again. Today I swapped out my old 6-button OBC for a 13-button one. The swap consisted of the 13-button OBC, wiring harness, and turn-signal stalk. The stalk was a pain in the butt, and quite honestly was the easiest part of the whole thing. Putting the OBC in consists of disassembling pretty much your entire dash content, with the exception of the dash itself. All center switches were taken out/popped out, radio removed, steering wheel removed, instrument cluster removed, steering column cover removed, and a bit of my sanity removed. The wiring harnesses are held together by clips that are kind of "built-in" the dash, kind of like the adhesive-backed things you could zip-tie things to. The only difference is that these plastic cable-holders are so old that they break. So, in essence, you can't reuse them, and I learned that the hardware when I tried to put back my instrument cluster. The wire bundles are supposed to run along the top of where the cluster would be so that the cluster itself can actually fit into that tight space. I tried to shove the cluster in with the wires along the rear but the damned thing wouldn't go in. Since the cable-holders were broken, I couldn't reuse those in any way, including zip-tying the cables to parts of the holder. In the end, I wound up using velcro straps to wrap around the cable bundles and then another piece of sticky velcro lining the top of the space so I could stick the cable bundles on the velcro, holding the bundle up enough to allow the instrument cluster to slide in. Anyway, I did test the OBC at point one and found that the brand new light bar that BavAuto sent me is non-functional. The OBC display doesn't light up at all, while the buttons do. I tried the light bar that came with the OBC and the one from BavAuto and neither worked. Is there anything that could prevent the light bar from working? Is it really possible that both the old one (more probable) AND the new one (not so much) don't work? Yes, my car is put back together so I will have to redo about half of the work at some other time, but before I do that, I want to order what I need so I don't EVER have to go through that hell again. The coding plug - I looked up some coding plug part numbers that are supposed to be used for the different engine types. The guy I bought the OBC from said it was from an '87 325is. The part number on the OBC seemed to correspond to the plug used for an E30 M3, and I have a 325e. I seriously doubt it is from an M3, so my question is, would this plug work correctly for my car? I mean, the only difference that I know between the B27 and the B25 is the rev limit (and power obviously), so why would it require a different coding plug?