Need Switched Positive power lead location.

I'm installing some electronics (again) and need to know if there are any ignition-switched power wires other then the mirror and radio power leads somewhere under the dash where I don't have to take the dashboard apart to get to.
 
I know where the trailor one is but that is hot all the time.  I need one to tap into for my GPS that is only hot when the ignition is on.  This is a very low-power drawing plug so it doesn't need alot.  I was powering my GPS charger and my radar detector all from the mirror power with no problems, but I don't want to take all that back apart to tap into it again.  I'm trying to be a little more organized with the wiring.
 
If anybody knows of one and where it's located along with the color(s), let me know.  Thanks!

I THINK the Pin 16 12V+ wire on the H3's OBDII port is only active during ignition.  I'll test that.  I'll probably use that if it's switched.

Where is that plug? Is it in the steering column or behind it? How much current can you draw without shorting it out?

that should be under teh dash near the steering column....current shouldn't matter cause you should be using a relay in anything your adding anyway, just use that wire to trigger (energize) the relay and your good to go as big as you want.

The first time I started using relay's was the older generation Radio Shack ones.  They were 25A.  I had that one burn out on me with half the load, and then found that everybody was having those same problems with their relays.
 
They found that the company making them was for sh!t so they switched to a new company.  The new ones work great.  I haven't had a problem yet.
 
Do you have any suggestions for a good relay, or should I just stick with the Radio Shack ones?
 
I'm so conditioned to using direct taps, I didn't even think about the relays.  Thanks Mike for your help.
 
Is there some kind of master relay panel you can buy for connecting all of your gadgets or do you just stick with a separate relay with a separate power block?

you can use a power distabution block if you have a crapload of stuff to add...but for most stuff it's not needed. I use bosch fuses and never had a problem with em....I think I got 50 of for like $15 on ebay last year/

I just saw that on ebay.  You can buy a crap load of them for nothing.  I may just do that. I only need one or two at the most, so I'll probably just march my happy ass over to Radio Shack and get some today.  I already have one at home from the infamous light bar that I can use
 
 

you can always use a fuse tap (add-a-circuit) for the easiest install if your not installing something with a big amp draw.

these are really awesome and simple to work with....most people don't even know about them.

they are great, they reatain your stock fuse without adding amp draw to it and gives you a fused wire lead...talk about plug and play...just don't get any easier.
 

That's awesome.  I didn't even know they existed
 
Can you get those at any auto parts store, like Pep Boys, etc?  Unfortunately all we have around here is Auto Zone and Advance Auto Parts, both which have hardly anything.  I have to drive 10 miles just to get to a Pep Boys.
 
I was just going to use the trailor B+ power lead under the dash.  I thought that would be easiest.  That's what I was using for my AC power inverter.

no you can't get them at local stores....at least I never saw them. I get them from my distributor that I used when I installed car audio/video for like $2...but I don't have any on hand or I'd send one to ya. This place is awesome for everything you could need...but be careful...they have such good stuff that yur bank account will take a beating.....I spend over $8000 with them when I was building the system in my Dodge...LMAO...they also have a $25 min. order..at least they did last I ordered.
 
http://www.partsexpress.com/pe/showdetl.cfm?Partnumber=071-580

I know what you mean about those kind of places.  I just found a place that makes all kinds of unique AV connections for home theater equipment.  They have stuff nobody else makes, and they make their own stuff.  I spent about $200 there on my first visit.  I'm afraid to go back on their site now

for some reason I got wrapped up in the moment and bought bulk speaker wire....I still have about 300 feet left...LMAO....my wife hates me

Bosh relays are great.  Potter & Brumfieldare very good. 
I wouldn't trust any other relays.  Some times the off brands are relabled P&Bs or Bosh and are fine.  Hit a junk yard and raid a fuse box as they will be relabled Bosh or P&B.... if you are installing lots of stuff, take the whole fuse box.
 

Those fuse taps would have been great for my various installs.  I didnt know about them either.  I just found a key-on hot wire and quick connected into it with an inline fuse.  Fuse taps would have been so much quicker.... 

you learn lots of tricks when you do it for a living....professional shops have lots of cool little gadgets.