mach 460 - aftermarket HU turn on thump?

[Tors]

I just installed an aftermarket HU (pioneer deh-p390mp) in my 2000 mustang gt with the mach 460 system. I used the Metra 70-5510 with the rca plugs and it sounds great, very solid bass.

but, I do have a slight problem.

whenever I turn on the car (engine and all), I hear a thump coming from the speakers. it's quick but very annoying, and after that, the radio works perfectly.
however, if I just start the car battery and no engine, it does NOT do it.

also, if I already have the car running and I take out a cd from the cd player (so it goes back to the clock on the unit), then switch to either the radio or put another CD in, it ALSO happens.

I tried wiring in a 1watt 1k ohm resistor in with the blue remote wire (aftermarket turn on), but that didn't solve the problem like I'd hoped.

any ideas?

 

[Tors]

FIXED.

I had to put a resistor on the factory plug's remote turn on, I had one on the aftermarket radio's turn on.

 

[neevnav]

Where?

Where did you get the resistor, because I just put a new HU in my girl's 99 and am having the same problem.