Ok, I can't seem to find the problem so I'll ask you guys. I've got a '93 touring with the infamous Bose system. The problem I'm having is that the driver's door speaker only hisses (very loudly) about 50% of the time. I know it's not blown...it does play about half the time. When I put the key in the ignition, it either hisses or it doesn't. However, it never goes from hissing to playing or visa versa. It only changes if I turn off the car and restart. I've taken off the door panel to check the wiring harness, and everything seems fine. I'm at a loss with this one....any ideas??

 

When you took off the door panel, you checked the speaker right? When a speak is blown, it will still make sound, just has a crackling noise. The hiss could be some sort of interference. Perhaps some ground wire in your head unit got loose?

 

Yeah, I looked the speaker over pretty well. Like I said, about 50% of the time it actually plays fine (no hissing, crackling, etc.), but the other half it just hisses (no crackling or popping). I was wondering myself if it might be interference, but I'm not sure from what. I'll slide out the head unit and check for a loose ground. Any other ideas?

 

there is an amp inside the door enclosure. You need to find out where the signal is getting lost. My guess is that there is a bad solder in the head unit, or on the amp board. Figuring out where the problem is will be a first start.

You might also be able to connect output for the passenger door to the driver's door speeker. If it then works - you know the problem in the head unit, etc. etc.