Radar detector install in MZ4 roadster

In case anyone is interested, I posted some basic instructions for a radar detector install:
http://forums.bimmerforums.com/forum....php?t=1520790

On a similar note, I'm trying to install a Homelink UGDO (Universal Garage Door Opener) in the cross member above the map lights. (from eBay ~$20 which is a lot better than ~$700 for a BMW mirror) Over the weekend, I popped out the map light assembly and confirmed there is enough room in the frame to fit the Homelink unit. I know from other posts that the purple/white wire that runs through that area is hot when the ignition is on.

So do you (or does anyone) know which wire to tap for neutral? The Homelink needs neutral not ground.

Thanks.

Originally Posted by courtier

So do you (or does anyone) know which wire to tap for neutral? The Homelink needs neutral not ground.

I could be wrong, but in DC applications, there is no neutral and it could just be that you got a hold of instructions with a bit of bad translation.

very very clean! this will be one that i do.. when i get a RD. haha

OK, so here is a picture of the Homelink unit. It has two leads coming off. I have tested it with a 9v battery and it won't fire unless I connect one lead to the + terminal and one lead to the - terminal. Admittedly, I am not an electrical engineer but it seems to need positive and neutral.

Anyone know of a neutral wire to tap off of?

Originally Posted by courtier

OK, so here is a picture of the Homelink unit. It has two leads coming off. I have tested it with a 9v battery and it won't fire unless I connect one lead to the + terminal and one lead to the - terminal. Admittedly, I am not an electrical engineer but it seems to need positive and neutral.

Anyone know of a neutral wire to tap off of?

http://en.wikipedia.org/wiki/Ground_and_neutral

Ron's link is fine for an explanation of 'neutral'. It's an unfortunate term for the average consumer. It's also a term that's only used for AC mains wiring, not for DC wiring in a vehicle.

The correct term for DC in a vehicle is 'ground'; there is no 'neutral' separate from 'ground'. Typically any solid brown wire in a BMW.

Originally Posted by dwm

Typically any solid brown wire in a BMW.

I only found one on the Z3-M coupe sunroof switch.

Originally Posted by Ron Stygar

I only found one on the Z3-M coupe sunroof switch.

Yes, as your diagram shows, sometimes the convention isn't followed and/or the wiring isn't as documented. In the Z3 M roadsters, the hot and ground wires for the dome light swap colors mid-harness (connector in the passenger side A-pillar).