I'm putting in a Gentex Compass Mirror and it says to use only an ignition wire for power. (Other power wires are on continuously and would drain the battery.)

PS - I've checked my manual, but I couldn't find anything that would help.

 

there are a few ways you could locate an ignition wire. one would be to look at the fuse box inside the vehicle and link the fuse to its wire on the other end. another way would be to tap into the IG wire running into you alternator. if you look on your alternator, the IG wire will be clearly labeled in a diagram, that is the ignition wire. you could splice into that anywhere along the line...i think mine was yellow w/ a green stripe, but i cant remember for sure. a very easy way to test if you have found the an ignition wire is to turn the key to the start position, but do not start the vehicle. touch any sort of power tester (ie - screwdriver shaped probe with a light inside and a groung wire running out of it) to the wire with the key in this position, and you should light up...then turn the key off to make sure the light goes off with the key. You'll be able to figure is out no prob...hit back if you need any more clarification.

Billy

 

Very helpful, brother Billy. Thanks.

 

DO NOT USE A TEST LIGHT. This is a great way to cook the electronics on modern vehicles. Invest in a multimeter so you don't damage your vehicle. I've even heard of airbags being deployed by poking around under the dash with a test light. You've got a $30,000+ vehicle. Invest in a $30 meter.