Relay or Not? for a remote starter

After searching the forums for a while, i realized i still don't understand electrical at all. Sorry if this issue has been covered but I'll explain anyway. I am using an SMS controller in my car to perform a few functions. One of which is a remote start function. With no key in the ignition, I can start my car (which has a BOA remote starter that I installed in it) by simply grounding one wire for 1 second and like magic my car starts. The SMS controller is what i want to to use to ground the wire. The controller has an output of about 500mA. My question is how do I use the 500mA to ground a completely different wire without either wire connecting? Any help or direction is appreciated. Thanks!

Use a relay. Look at the diagrams for a relay with a positive trigger and a negative output. or ground pins 86 and 87 of a relay..put your 500 ma trigger on 85 and the wire you need grounded on 30...piece o'cake

Sounds almost too easy. If I choose to ground those pins, should I ground them seperately or could I ground them at the same location? Thanks Again!

you can use a jumper to go from 86 to 87 or vice versa and then connect it to a factory ground point...if possible, otherwise any metal point is okay...

Thanks a lot!