wiring an accessory to ignition on power

I am trying to connect an accessory to my truck (2004 Chevy Silverado 1500) and ONLY want the thing to come on when the ignition is on. I don't want to be able to turn the thing on when the ignition is off and/or key is out of the ignition. Where would be the best place to connect to for the power supply? I was going to splice into the ignition-on wire on the back of the radio but there has to be a way to do it without tapping into the radio's harnesses. Can someone guide me where I should connect the power supply to? Also, help me locate where the connection place would be on a 2004 Chevy Silverado 1500. Thank you, in advance for your help! tkpopeye

what is the accessory?Dustin Rockney

Rockstar Autosports

There is not a switched wire on the back of your radio.  There is a pink wire at the ignition harness that goes hot with the key.  However I do not think it will handle the current to even power the coil of a relay.  If nobody can find you a suitable wire, I do have a diagram using a transistor that will allow the pink wire to trigger the coil of a relay.  I know that some of the vehicles do have a wire in the fuse box.  If this vehicle does not, I will post a diagram for the transistor circuit.

It is a Lamp (LED lightbar) for plowing that I want to connect to the ignition-on wire (pink wire). I'm not sure about the amperage or any other specifications of this unit. It came with just the black (neg) and red (positive) wires, with which the red wire has an in-line fuse. I do not know much about electronics but know the SIMPLE basics. I don't know about relays, transmitters, diodes, etc. But I will be able to wire this myself (HOPEFULLY). Thanks again!

Simply put what you are looking for is the wire going into the fuse box, either in the vehicle or under the hood that goes live with ignition before the fuses. Solder onto this wire, then to be on the safe side, take it to a relay 86, your original fused lead, again from that fuse boxe's constant 12v+ supply (i.e. before the fuses)  to relay 30, lamp out from 87 and 85 from relay to ground along with black from lamp.

Thanks Howie, but you lost me. I can't quite make out what you are talking about, in regards to the relays and their numbers (i.e. 85, 87, etc). Is there an easier way to explain this? Sorry for being so clueless with this, but I am lost. Thank you!

Is this something that is in the truck already or do I need to purchase it separately at Radio Shack or somewhere else? Also, can you clarify the connections? The numbering makes sense but I am not sure as to the exact wiring. Would you have a schematic of this type of connection?