External speaker in door?

[skatertj]

So, I have a intern at our local fire house. The other day, i decided to hop in the impala and turn it on to view the lights it has. On second turn of key the radio came on with the rest of car electrical. I noticed that the cars radio and fire radio were both putting out sound. But, the fire radio sound was coming from the drivers side door speaker. I dont recall if the radio was coming from that speaker also but i do know the radio station was going through the rest of the car and fire radio sound was from drivers side speaker.
Is it possible that they somehow have it wired to run through that speaker and the other speakers run standard FM radio? Or do you think its a external speaker in that door? I want to do the same to my car cause it sounded nice!

 

[FFPM571]

Police package cars have the option to use the front speakers for the radio.

 

[skatertj]

I have a 01 crown vic ex cop car. How do i access this feature then? Haha

 

[n9mxq]

Just unplug the factory harness from the speaker, and run your harness to it. I did it in my 87 Dodge D-50 pickup. Left dash speaker was my VHF radio for ESDA, Right was Ham radio..

 

[FFPM571]

Crown vic has a plug in the passenger side kick panel up under the dash.

 

[skatertj]

Is this harness something i need to make? Or can i buy one? If i need to make it, do i just need a 3.5mm "ear phone" plug and some wire?