Hey guys,
I had an aftermarket headunit installed for a few months now and this was connected to the stock non-pioneer speakers.
Today, I replaced all the stock speakers with aftermarket ones, connected them to a 4 channel amp using 14 gage speaker wiring and connected the amp to the headunit using RCA cables.
If the engine is off, the system sounds fantastic, but if I start up the engine, I hear some kind of higher pitched squeal or feedback coming from all 4 speakers.
I'm wondering if this is due to a bad ground on the headunit or possibly the amp...

Any suggestions are appreciated!

 

Ground may not be good. Either that or a wire is attenuating out somewhere affecting the whole circuit.

 

You sir have alternator whine! Check all your wire connection and make sire they are solid. Cobalts are kinda known for the whine. For a quick fix use some ground loop isolaters (GLI) you can find them at a radio shack. That hopefully should solve your problem.

 

u will also get engine whine if u run the rca or speaker wires next to a power wire for the amp.

 

You have either ground loop, or like said above your RCA's are picking up the 12v electrical frequency because they are too close to a 12v power source. Make sure all your grounds are secure and have a clean connection to the body or chassis ground. To see if the problem is in the RCA's, take an extra set that you or a friend might have or buy a cheap pair and unplug the RCA's you have now from your head unit and amp. This will eliminate them completely. Take the other set you have and plug them into the headunit and run them to the rear over top of the console, put down the rear seat and plug them into the amp. If the problem goes away then time to relocate your RCA's.

 

Ok, I'll see if I can fix it this weekend.
I'll let you guys know if it works!