FM Modulator and iPod Connector Wiring

TrainTrac · Feb 3, 2008

I bought an FM Modulator from Crutchfield for my 2004 Pioneer Adrenalin system and installed it today. Rather than using the included switch, I just connected it to the power source wire for the radio on the factory harness.

I purchased one of the connectors shown below (thanks to Jeff C for the idea). It sounds great when the RCA's are hooked up. However, I've had one problem: I hooked the 12v wires directly to the wires for one of the 12v plugs so that I'd have constant charging power to the iPod. When I tried the setup after doing so, I had no signal from the modulator. I had also purchased a RCA in-line ground loop isolator just in case. I hooked this up, and everything seemed to work just fine initially, but then my battery was sucked completely dry within seconds after testing everything.

I'm not sure what I did wrong. Should I have not connected the 12v wires to a constant hot source, but rather to a circuit that's only on when the vehicle's on? I'm not sure why this occurred, because it shouldn't be any different than using a standard 12v outlet plug to charge the iPod. Or did the ground loop isolator have something to do with it?

I bought the connector so that everything would work through one cable-audio and charging.

Any ideas?

TrainTrac · Feb 4, 2008

Gerald Pierce · Feb 5, 2008

Back to the basics -- twidget

(I can say that, I are one too)

check all the wiring. something is not right. Sounds maybe reverse polarity on the wiring? bad connection?

TrainTrac · Feb 10, 2008

I finally got my FM modulator and iPod cable wired correctly, and it sounds great. My original problem was that I connected the modulator's red wire to the 12vdc wire on the stereo harness that supplies voltage for the lighting in the radio. So when the headlights were off, the modulator was off! D'oh! :angry:Wrong 12vdc wire on the harness! So after a little more testing, I found the correct 12vdc wire and connected both the modulator and charging cable directly to the 12vdc source for the radio, so that they get power only when the key is on, like the radio. I then moved the ground for both the modulator and iPod cable straight to a bare metal chassis ground. And it all fit very neatly down under the console below the HVAC controls.

The sound from the iPod using direct line-level audio from the USB connector is very good. Much better than headphone jack to RCA's, and a tremendous improvement over using an over-the-air FM modulator previously. If you're looking for a way to iterface an iPod with a factory stereo, this is a good way to go.

The only drawback is that I'm getting some engine noise when listening to AM, so I'm going to install a filter. If that doesn't eliminate the noise, I guess I'll just go back and install a switch for the modulator, so that I can shut it off when I'm listening to AM.