Yes use the blue wire it turns on the factory amp if so equipped.....If your using an rca converter hooked into your factory speaker wires might want to invest in a real nice one and invest in an external crossover as u will be able to adjust the bass from this instead of pumpin the bass thru the factory rear speakers....Plus if you get a nice line converter you can turn up the output from it to give the preouts to the crossover a stronger signal....Most factory speaker output voltage is around 2volts....Most aftermarket stereo's rca preouts are from 4 to 6 volts so you can see the difference...I cant tell you how many install repairs I have done for friends and friends of friends that have killed there interior speakers by having to adjust the factory bass way up just to get the subs to sound good.....Just FYI and my 2 cents