Interface between BMW E46 steering wheel to control Pioneer aftermarket headunits
Tested with BMW E46 AT71 and Pioneer MVH-X380BT headunit.
In theory it should work with
- 3 series E46 1999-2005
- 5 series E39 1996-2004
- 7 series E38 < 2001
- Z4 E85 2002-2008
- Mini 2001-2006
This circuit / software is more than 5 years old so some details can be wrong. First the input would be taken probably from PIN 7 in the big OEM radio connector. The outputs OUT and RING goes to 3.5mm jack plugged on the backside of the headunit. Voltage would best be taken from the switched power pin.
The circuit can be done better, it was just a proof of concept. Better power supply, programming interface or the outputs optimization would make it a solid interface. It worked for about 2 years without any issues.