12V Constant & Switched Power
 

I know this sort of question has been asked before - but I have searched all the forums and can't find an answer that addresses my needs. If anyone can help I would really appreciate it.

I have a 2003 E46 M3, and have fitted a speed camera detector. I have the GPS aerial on the back shelf, a laser detector on the headlining by the rear-view mirror and the display unit on a Brodit Proclip over the driver-side air vent.

The control unit is behind the steering-wheel panel.

Everything works fine, but at the moment I am running it from the cigarette lighter. I need a source of 12V switched and constant power, as well as a good grounding spot. There are quite a few thread all over the place about this, but none of them really do the trick.

1) Power from sunroof/garage-opener. No good, I don't have a sunroof, and there is no removable panel in the headliner.

2) Power from back of radio. I have MkIV Nav system, and I can't for the life of me get it out. I have had all the trim and the vents out, but I can't release the (I assume) spring clips holding it in.

3) Power from armrest console (i.e. telephone harness). Possible, but I don't really want to be ripping all that out.

4) Power from trunk/boot - seems like an awful long way to go.

5) Power from ignition wires - this seems like the best bet, but the only DIY I found on it was for a 330, and the red/green wires he referred to don't seem to be under the panel under the steering wheel. The only wires I can see are for the OBD.

Anyone have any input or ideas?

Thanks in advance

I'm not getting it. Why do you need constant power? Do you plan on speeding with your engine off?

When I fitted my detector I got the switched live and the ground feed from the brake light switch connector this is easily accessible after removing the storage compartment on the right beneath the light switch. If its working properly fed from the cigarette lighter I can't see why you need a permanent live?

thanks for that - I will take a look tomorrow under that panel.

The reason for wanting to not use the cigarette lighter is that it looks a little unsightly with the wire trailing across the top of the shifter area and under the steering wheel.

Also, the only reason I wanted consant power was because the wiring diagram & instructions for the detector indicate that it should be connected in that way. I am sure that if I just hooked up the switched then it would be fine, but given that where you find one you tend to find the other I thought I may as well do it 'by the book'

thanks for your help

The nav has a clip on each side, at the bottom, you need to open the face, then stick a tool on each side (you can probably get the tools from the dealer, should be cheap). You could also use a pick to slide the clips out.

You could go to the fuse box. If you go to the ignition harness, make sure you use a fuse inline to avoid a potential fire hazard.

Getting to the phone harness is not too bad.

Hi ca1242,

Many thanks for that - I looked at getting the NAV out, but for some reason it never occurred to me to have the face down to find the clips....must have been a bit slow that day.

Does anyone have a link to a wiring diagram of the harness at the back of the NAV, before I start hacking into wires?

cheers

Not sure about non-us wire codes. Look for a violet wire with another color stripe for switched ignition, brown for ground. Check with a voltmeter to make sure you have the right wire.