Out of the blue alternator whine: solved

I have an amp running my door speakers, and also have subs in my 1st gen. About two weeks ago while riding down the road my speakers all of a sudden cut off, but the subs kept working. It was in Bluetooth mode, I switched sources and everything started working again. Fast forward a week and it happens again. However, this time I tried to switch sources, and nothing happened...but then the subs started a a very loud hum. To the point that I could smell the coils heating up...or something electrical at least. After that happened, i shut the HU off. Later, everything started working again but now I’m getting engine noise/alternator whine through my door speakers.

So far I’ve redone all the wiring for the HU. I’ve also ran a different ground for it. I’ve checked and redid the ground for the amp running the door speakers, and also went and bought a new amp with new RCAs, still haven’t made it go away.

The only conclusion I’ve come to is the HU is to blame. If I unplug the RCAs for the subs and also the external mic, the noise decreases but is still present. Also, if I mess with the HU wiring harness right where it connects, the noise will come and go. I’m at a loss and not sure what else to do other than buy a new HU. Any other suggestions on what to try?

 

did you check the battery ground by chance? make sure its clean and tight?

 

I did, everything appeared to be fine. I’ve noticed my voltage staying around 12-13 when at idle, especially with my lights on it will be around 12v at idle. So the alternator may be getting ready to go out...not really sure.

However, I solved my issue for now. After some google searching I found where mainly Pionneer radios have a pico fuse that can blow. And as a solution, people were grounding the RCA outputs. I did similar to the attached photo, wrapped some thin gauge around the outputs, and then ground it to the HU chassis. I also ran a ground from a screw on the HU chassis down to the bolt where I grounded the HU wiring harness. So far so good, it has appeared to clear up all my problems. With it being a cheaper HU and a few years old, I wonder if a internal ground hasn’t gone bad.

 

very cool solution.

 

Whoa! Never seen this done before. Thanks for posting up!