I have a 94 toyota pickup with a Panasonic stereo. I bought 2 speakers to add, so i can have 4 speakers. My problem is that i install them and they are not working. I wire them to the 4 wires from the deck, which they are green,green/black, purple, and purple/black. Is there another wire i have to wire for them to work. I never ran into this problem i always have install speakers this way. Unless in Toyota pickup are different.

 

Check your wiring again, then maybe the fade and balance? Not a Toyota question but a Panasonic one.. Odds are if it's wired right and the knobs are not set wring someone blew the channel in the head unit.