2003 Lincoln Navigator, Afrermarket Nav w/Factory Sub

Hey everyone, I'm hoping someone can help... I have a 2003 Lincoln Navigator Ultimate with a premium sound system. All the speakers are amped, and it has a factory sub I want to keep. The factory head unit is simply out-dated, and I want some more features, so I bought an aftermarket unit. A Joyous J-2612MX double din head unit. Does everything I want, and only $200. Less than the disc for navigation on the factory unit. I bought every aftermarket wiring harness I could find, for the vehicle, but none fit. I just decided to "hard wire" the stereo. I've installed around 50 aftermarket stereo's before, and never had issues like I'm having. The speakers produce sound, and all the gadgets seem to work. However, I'm getting a lot of noise from the engine, and from static feed back, even while the vehicle is off. I'm also not getting any response from the subwoofer. Upon all my research, I've found out that the amp turn ons require a 6v not 12v signal to turn on, so I have done that, and still nothing from the sub, yet all my speakers have always worked, even while I was sending a 12v signal. During my research, I also found that engine noise is common, and a ground isolator was suggested. So I tried that, and still nothing. I know grounding is usually the issue with noise, so i made sure my grounds were good, and they are. I'm at a loss for what to try next, please help.

are you using the speaker outputs to send a signal to the factory amp or the RCA outputs? if you have not already cut the plugs off of the harness would you be able to post a picture of the radio harnesses and a description of which wires you connected.

I have connected the speaker wires directly without the factory plug. Just as one of the factory plugs would have done. Now that you mention it, I should try hooking up the RCA's to the factory speaker wires, as they should be amped. Perhaps I'll try that. However, I'm not getting any sound from the sub which is amped, so i might not get any sound at all if I use the RCA's. I did re-check my 5v signal, and the resistor setup I'm using is not the right one, as it was outputting 9v, which is why the amp was still not working. I did order a 12v to 5v converter though, so that issue should be fixed at a later time.James

i think the wire harness you need will have RCA connections instead of wires for the speaker outputs. this could be why you are getting so much noise because you might be sending a high level signal to a low level input. if you ignore the noise does the volume of the speakers get really loud without turning up the radio that much? its been a long time since ive done one of these navigators. also are you totally sure that your navigator is an 03? there is a big difference between an 02 and an 03 when it comes to the radio install. check these out and tell me which one looks like it would fit... 02 navigator harness 03 navigator harness i just re-read your post, are you saying that you already cut off the factory harness?

First off, yes I'm sure its a 2003. Secondly, yes, I cut the factory harness, but if need be I can re-connect it. After you asked me if I had the speaker wires connected, instead of the RCA's, everything clicked in my brain. Of course I'm getting noise because of this. It didn't dawn on me before that this whole system is amped, and I'm going to have to hook up the RCA's. Always the simplest things huh. Once I get my 5v converter, I'll hook everything up, and I'm sure the issues will be solved. I'll update when everything is hooked up. Thanks so much!

as a test first i would get a cheap line output converter to convert a speaker output into an rca just to see if this will work and so you dont have to risk hurting the radios RCA outputs until you are sure this is the problem.