All US BMWs are prewired, overseas vehicles are a different story. There is an ibus wire present on your factory HU at PIN7 on the harness:



Terry's correct. There are other locations, depending on if your M3 is prewired for telephone or not.

__________________
Tom G. | european auto source (eas)
email: [email protected] web: www.europeanautosource.com
tel 866.669.0705 | ca: 714.369.8524 x22 | fax: 714.908.1796

Twitter | Flikr | Facebook | YouTube