I have a g35 with the bose system BUT with a pioneer avic-d3 HU. (so this cannot be the bose HU problem!)
This has not happened before and arised a couple months ago.

if the HU is turned on at low volume, the left speaker will not work but will cut in when the volume is set to 9 or above.

and after that if you turn it down again, it will still work until very low volumes like below 2 or when you turn it off.

It happens almost everytime and I know it happens in G35s with the bose HU but the problem is I have an aftermarket HU. this shouldn't be happening.

What i would like to know is that if this is a HU problem or speaker problem?

 

take it to the dealership if ur car is still under warranty.

 

but it has an aftermarket HU i doubt they'd work on my car.