If one speaker on the left side were out, then you suspect the speaker and/or wiring. But if both speakers on that side are out, the suspect the radio.
In your case, these radios are notorious for failure in this exact manner.
Changing the factory radio won't be a problem. And you won't have to worry about that silly securty code ever again.
You could go to Best Buy and purchase a wiring harness which will plug directly into the factory harness. Then it's just a matter of changing the radios out. (You'll probably need an adapter to make the new radio fit properly, which Best Buy can also supply)
Wednesday, September 15th, 2010 AT 6:30 AM