This is a really easy mod and I know it's very popular, especially in our local group in AZ. I did this two weeks ago at our club tech day. I put the outlet in the passenger foot well, in the hard plastic piece around the head unit/frame brace. Since it was so conveniant, I just tapped 12V and ground from the accessory line of the head unit.

I noticed that when plugging in my GPS (Magellan Roadmate 3050T) and powering it up, I would lose my amp (JL Audio 500/1). Found out after some testing that the load on that circuit (50W/Channel head unit w/4 speakers, Modifry DCI and now GPS) was too high. With everything running, the voltage drop on the power antenna line was too great and the 12V signal sensing circuit of the amp (which was tapped into the power antenna behind the seats) wouldn't read high enough to turn the amp on.

I figured the easiest solution was to rewire the power outlet straight off the ignition 12V at the block under the dash, and now it works fine.

Just thought I'd give a heads up for anyone who uses the 12V signal sensing off the power antenna to keep an eye on loading on that circuit.

-Zonie

 

It may not be the same issue, but when I added an outlet for my Nuvi 350, if the Nuvi is plugged in when I crank the starter its power supply turns itself off and I have to unplug and replug it to get power back. If I remove the Nuvi from its cradle before cranking then the power supply stays on. Drives me crazy. I'll have to see if the lead from the ignition block works. It's a bitch to reach, though, isn't it?

 

Guys, you have to be careful with this sort of stuff. You can't just go tapping wires. You have to know the current allowance of the circuit (in the case of the power antenna lead) and the demands of the starter motor.

Just about anything plugged into the 12V supply will lose power when you crank the starter. Even the in stereo and dash cluster shut off.

 

And if they don't shut off you need to be careful of cranking while the fancy electronics are powered. A friend of mine fried 2 monitors and a VCR in his truck by leaving them powered when he cranked it up (over a month's time, didn't fry on the first crank).