Haven't updated this thread in a long time. The car has been very spoiled in the last 2 months...
Both front window regulators have been replaced. The passenger side had a crappy aftermarket one that sounded like you were tearing nylon when the window goes up or down. It was something inside where that cable wraps up that was doing it. Both regulators I zip-tied like the thread on here, so hopefully they don't go bad for 10+ years.
Next, I got a switch center from an M3 with the tire pressure button and sport button. I ran a wire to the DSC for the TPMS and also installed a v2 Sprint booster I bought new off Ebay. The TPMS I coded, but doesn't work because my module is CI-12 and not CI-13. Bummer. But the sprint booster works great. I wired it in totally different from the write up on here, and made a schematic of the two-wire sprint booster button, for others in the future:
Measuring the voltage across the black and red wires going to the switch, voltage is near 0 volts when the thing is in normal mode. In green mode, the voltage is positive ~5v and in red mode, the voltage is negative ~-5v. That's why the red LED needs to be flipped in circuit to work.
I did not unsolder anything from the sprint booster switch itself. I just added wiring to the relevant spots and ran the Sport button and new LEDs in parallel with the sprint booster components.
Here is the sprint booster untouched:
And here it is with the wiring soldered:
I added a BMW connector to the new wires, which will go to the new wires from the switch center. This way things can be easily disconnected if removal is necessary in the future.
I will make another post with what I did with the switch center. I used the factory pins in the back for the actual switch, so no switch replacement or modification is necessary (from the factory, the switch is designed to just ground the pin it goes to on the DME), and only added wires for the new LEDs.
'04 330i ZHP sedan | Mystic blue | Alcantara | 6MT | 111k
'98 740il | Schwartz 2 | Sandbeige | 5AT | 238k | lowered on Bilsteins w/ B&G springs
'00 540i sport | Titanium silver | Black | 5AT | 120k
'85 Mustang GT convertible | Medium charcoal metallic | Gray | 5MT | 215k | one owner, all original