We have wired a new aftermarket radio and its turning on but were not getting any speaker audio we do not have the j1850 and the PWD wire hooked up and not understanding this at all PLEASE HELP ASAP

 

What is the year and model of the car?
With some of the cars built in the last 15 years or so the computer controls the factory amp volume and those cars need a PAC can-bus adapter.

 

Yeah if you tell us year and model we can help better ?

 

I haven't found a factory made cable/harness that works, so I built a circuit based on a handful of parts and an atmega328p.
The codes to send to the bus are:
8D 0F 41 - Amp on
3D 13 00 00 - Volume zero
3D 14 00 00 - Pan/fade center
3D 15 00 00 - Bass/treble neutral
3D 13 18 - Volume 18 (of 32), a resonable compromise.

The message, except Volume zero, should be retransmitted every 850 ms.

My device also translates the steering wheel remotes to NEC remote signals that an Alpine head unit understands.