Recently had a Rockford Fosgate amp installed for my door speakers. Problem is that the amp is picking up electrical interference from somewhere and relaying it to the full ranges in the dash. A constant high pitch ringing noise. If I disconnect the inputs to the amp, the noise goes away. So it’s the signal not the amp. I’ve had this happen before on a previous vehicle with the same amp. The noise would stop if I turned off the DRLs. This time it’s not the DRLs and I can’t find anything that turns off the noise.
HOWEVER the noise does turn off when the vehicle is turned off for about 30 seconds but with all the audio and infotainment still running. Ground loop isolators didn’t work, different RCAs didn’t work, moving wires around didn’t work. Any thoughts or solutions?
Just to reiterate, SOMETHING is being turned off during those 30 seconds and that’s when it noise goes away. I just don’t know what.