Hi, I'm in need some urgent help.

Car is in the shop right now, and they have isolated the issue (a ground loop-like engine noise coming through all the speakers) to be caused by the AVIC-F900BT head unit after trying many grounding locations and all of the other components separately

This is actually DIAFTIA's F900BT head unit (forum member, I bought the car from him with the unit in it), I contacted him as well but he was unaware of any such issue or fix.

Basically they are trying to tell me that the RCA outs of the F900BT have an issue and trying to sell me a line driver (Audiocontrol Matrix Line Driver) and saying it could minimize the issue.

Are you guys aware of this issue of the RCA outs going bad? Is there a known issue/repair thread on this? Thanks for any help or advice.

Take to an audio installer. How long ago did you buy the car from him? I have never heard of engine whine being associated with RCAs unless running on an amplified line.

Yeah, there are 2 amps. And the car is currently at an audio installer. They are pointing to the AVIC causing this noise.

So it's having alternator whine? Did they separate the running lines? Like RCAs and turnon up center of car while AMP hot up side? Ground real close to the amp (under 12 inches but also 20 inches apart from each other?

I've shipped the unit off for repair, will update once it comes back! Thanks

pioneers are know for developing a bad signal ground or blowing pico fuses that can/will cause a bad alternator whine.

been covered many many time with a few different fixes.