Hey, I got a 2008 2.2 cobalt Lt with the basic radio. I installed a pioneer single din radio about a year ago and it was all working fine until it just stopped playing. The radio comes on and it shows the graphics that music is playing but now sound comes from the speakers. When my phone connects, the back speakers make a “thud” sounds but after that. Nothing. Any ideas on where to start. Other than the radio and harness.

 

Connect another speaker. If it works, all your speakers are blown.

 

I had to swap head units. So I put the oh radio back on but I noticed that my rear passenger speakers were not working. They are a component set but the crossover only works if the positive is connected, but as soon as I connect the negative, no sound comes out. When I switch negative and positive, I get a night pitch beep. Could it be the crossover itself ?