Hi. Your best bet would be to hook up to the output side of the pcm relay in the battery junction box under the hood. That way when the key is on, there will be power for your relay.
Which is the pcm relay? what would be the wire color to attach to?
Let me see if I can get a diagram real quick...
What engine do you have?
Click Here for relay location. Use the location for the 3.5 engine
I need to connect to which pin on the relay?
Hold one sec...
There are only 4 pins on the relay. They are labelled 1,2,3,5. Connecting to pin 5 would be power when the key is on.
Wiring Diagram for PCM relay