So, as I was driving the other day, the volume on my stereo almost completely dropped out, and after messing with the controls (iPod, Radio, etc.) I just turned it off. The next day, when I tried it, the stereo seemed to be working fine, but when I turned the volume up (around 45 on the OEM head unit), the sound was really fuzzy in the front left speaker. When I fade the sound to the back left it sounds the worst, but when I fade it to the front left (the speaker that is the problem), it doesn't sound bad.

The next step was to take it to a family friend who has an aftermarket radio install business. After listening, he decided that the speakers must have just gone bad. So they replaced the speakers with some new Alpines, but the problem persisted. They told me that they now believed that the problem was within the head unit.

A bit of background: About 3 years ago I bought a set of the interior illumination led's (on scionlife), and installed them using the instructions from trdsparks.com, which involves tapping into the power from the cigarette lighter. And roughly 6 months ago, the lights suddenly stopped working.

So I figured that I would make sure that the head unit was the problem before I installed an aftermarket radio with a new wiring harness. I purchased a 2008-2010 OEM radio from a local used parts store (that I trust and that offers a warranty and guaranteed, tested products). After plugging this in, the problem was still there. [I guess it is possible that the new radio has the same problem as my old one but not very likely. The sound problem is exactly the same for both.]

Now I had to do some of my own troubleshooting (via the interweb), and after searching and searching, I couldn't really find anyone with my exact problem.

I have checked the fuses (I replaced the cigarette lighter fuse under the steering wheel, even though it didn't look blown), but nothing seems to fix it.

I have read that it may be a grounding issue, but it seems like those mostly happen when an aftermarket radio isn't installed properly. And it doesn't seem like my factory wiring would just "go bad."

Anyway, if anyone has any suggestions for me please help!!

 

Kinda sounds like an intermittent issue with the harness since you double checked the speakers and the head unit....did you look at the pins on the connectors? If it is the harness then it is going to be hard to diagnose it!