I just recently installed a new headunit into a friends 240sx, like as I did before without any issue. But this time around, I don't know if I did anything wrong but there's noise coming from the door speakers. There's a hint of noise/signal coming from them as he steps on the gas. I'm thinking It's either picking up the alternator signal or something else.(it might be the gain on the amp might be too high). Do you guys have any idea what it might be?

I have checked all the wiring and moved the ground around on the headunit with no luck.

 

your RCA cables may be picking up noise, try relocating the RCA cable and make sure you dont run the RCA cables with the power line. it can also be caused by a ground loop, if thats the case run a ground wire from the headunits to the amps ground.

 

It might be the RCA cable possibly. I didn't clearly check where the power cable was ran(dont know how/where the previous owner ran the wires....) I'll look into it.

Thanks for the reply.

 

Also Verify you have a good ground