Originally Posted by crystalworks

You are going to have to run a relay setup for the reverse cam trigger wire. The lights are PWM signals (for some reason) so they aren't enough to power the backup camera when the backup lights are turned on. It's been discussed before and a search should turn up the info. If after you hook up the camera, you just get a black screen instead of an image, this is your problem. I'm not sure if it only affects post LCI trucks as I only have experience with a post LCI.

And yes, all the solid browns in BMW's are ground wires. Any of them will do.