As posted on g35driver.com
Guys/Gals,
I experienced the same problem with my non-BOSE headunit today. The driver (left) side speaker output was very low compared to the passenger (right) side when listening to the CD. The radio output levels are fine.
I preformed the following to diagnose the problem:
1) Checked the balance setting.
2) Reversed the inputs to my amp and verified the problem is with the headunit.
3) Switched to another disc in the changer with no positive outcome.
4) Verified the radio output was okay.
5) Ejected all 6 discs from the changer and reinserted one disc.
<font color="red">The single disc I inserted played fine!</font id="red"> Perhaps when I ejected all the discs the headunit reset itself. This leads me to conclusion that this is not a loose connection issue, but a problem inside the headunit.
I don’t want to do this on a regular basis, but I’m glad everything is working okay once again.
Let me know if this solution works for you.
'04 G35 Coupe [

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http://hiddensub.info