Ok guys, I got a varad interior kit. There are three primary wires to connect; the red wire battery positive and black wire negative ground wires are easy. However, there is a yellow wire ignition (+12v when ignition is "on"). Where do I connect this wire?

 

Assuming those wire colors are right, (typically red is ignition and yellow is battery), but anyway, I dont know that product. So basically you connect it to something that is hot only when the key is on, The red wire (remote/ignition) on your radio harness would work fine. (at least I think its red).

 

Yes, you're right; sometimes the red is ignition and the yellow is battery. However, I checked the varad manual and red is battery and yellow is ignition. Thanks for the feedback regarding the a good source for the ignition wire!

 

No problem. I probably should add, that when a device just needs an ignition trigger (youll know because there is also a battery wire along with the ignition wire) it is okay to use this method. However if the device relies soley on the remote/ignition wire for power, (ie: theres no other power wire), then it is best to use a 12v automotive relay and connect the ignition/rem wire to the trigger of the relay, and use the main terminals on the relay to route battery power to the device. The power in that rem/ignition line is 12v, but it is very dirty and is full of interference, hence it is a bad power choice for something like a wideband or other measuring device.

Hope everything works out for you.