Hi all,

My girlfriends head unit (Pioneer) recently 'exploded' (I'm assuming a short circuit, as she saw sparks) and won't turn on. Upon inspecting the wiring, I decided to disconnect all speakers, rewire only one test speaker, and focus on the constant (yellow), red (accessory) and ground (black) wire. I began by running another ground wire straight to the chassis, to no avail. This suggests the ground wire is O.K. I then proceeded to connect the constant 12v and accessory wires, to check if the accessory wire was shot. This worked, and I concluded that either a fuse or accessory wire was kaput. Then came the puzzling part (for me). When I went to test the head unit using this crude wiring solution, the AUX input was almost completely static. I confirmed that the AUX was working. The volume could barely be turned up, and the sound quality was horrendous. Is this something to do with the accessory wire being run directly from the battery? Or is it to do with the actual speaker wiring? (I am fairly confident the speaker is wired fine). To further add to my confusion, when trying to replicate my accessory-to-battery solution, it no longer worked. I tried this with 3 working head units, no dice. And yet, when I ran a wire directly to the positive battery terminal, it worked fine. Does this indicate that a major fuse is blown, or both my constant and accessory wires are shot?

Thanks in advance.