Hey all, got an 04 FX4. I just replaced the factory 6 disc head unit with a pioneer avic f700bt. Bought the mounting kit and wiring harness from Crutchfield. Installed everything and all works well. One problem i think- when I start the truck up, after just a second, I get an audible "thump" through the factory sub. And while the key is on, you can hear a buzzing through the sub as well. The buzz is quite quiet and doesnt get louder with the volume. I rechecked my install and all seems good. The buzz is tolerable as you can hardly hear it, but the "thump" on start up bothers me. Any Ideas? is it the sub?

 

The 'thump' is caused by an overvoltage issue. The factory system uses +5v for the amp turn on lead, and your new pioneer puts out +12v. Now you are sending 12v to the amp turn on that is set up to receive only 5v. Don't worry the fix is an easy one, either install a resistor in series on your turn on lead to knock the voltage down or use a 5v voltage regulator from radio shack (connect the lead going to the amp to the 5v output on the regulator, connect the 12v lead from HU to the 12v input)

 

Cool, Thank you a ton. Do you think this is also the buzzing?

 

Might be.

 

 

How does that wire up?

 

Just like 05redFX4 (who has a blue truck) said. the 12v side goes to the avic, the 5v side goes to the truck.

 

solder it inline for the power wire? dont worry about the ground?

 

Nevermind, just went back and read.

 

problem solved, thanks guys