I know somebody already ask about this issue, I'm installing a new radio, but I'm not getting any sound out of the speaker, I check # 28 fuse, it's good, do the factory radio supply 12v to the factory amp ??, when I sold this shark, it had a factory radio and it work fine, after 5 year I bought the shark back and it had no radio, a bunch of cut wires, Thanks for your help.

 

The factory amp has it's own 12 v supply via the "choke" (that transformer looking thing).
The factory radio has a white wire that feed the power ant (is your car has one) AND splits and sends 12v to the factory amp to tell it to turn on.

Hope this is what your asking,

Dave

 

Thanks davek9, I will pull the seat up and trace the wire or check for 12v at the amp.