Ok so my stereo system is in sounds great, BUT now when the engine is running there is this high pitch squeal coming from the speakers (I think). It modulates with the RPMs of the engine and sounds like a ˟˟˟˟˟˟ dentists drill. WTF? Any ideas guys.

95 Runner, California Profile 4400 amp, Infinity Kappa 6 1/2'' in doors, MTK 3x 10'' sub in back.

Also now auto locks starting to not engage in the front passenger door, rear driver side door as of stereo install time. Did I puncture something while drilling on the back doors when I put speakers in.

Again, thanks

 

The noise is called alternator whine.

Did you run the RCA cables next to the power wire for the amp? If so, then you are getting the signal bleeding into the RCAs and need to isolate them from the power wire.

As far as the door locks are concerned, you may not have hooked all the switches back up when you put the door panels back on.

 

Yep, that's it then. I did run the power next to the RCA cables (doh, rookie mistake).

As far as the door locks though, I didn't detach them to put the speakers in and one of the nonfunctional locks is in the front passenger door which I didn't do anything to. Also they twitch like they want to lock but don't, unlock is fine.