hey guys ,,
today I'm going to show you an easy way to add bluetooth to any car audio player either old or new it works on almost all cars makes and models.
it's bluetooth adapter that is going to be installed internally to the audio player so we will make at almost a built it bluetooth. it is better than the other bluetooth adapter which connects to the 12v/cigarette lighter socket because that one transmit through FM also because of different grounds that the adapter and the audio players are connected to it will produce an annoying noise coz of the ground loops.

the adapter receive music from the mobile phone via bluetooth and transmit it to the audio player through the wires.

Step 1: About the Adapter

to install the Bluetooth adapter first you have to remove the audio player from the car

the bluetooth adapter has 4 wires which are :
12v

ground
left channel output
right channel output

the ground and 12v are easy to connect just hook them in the car audio player 12v and ground.

connecting the audio wires

now we have to choose a source in the audio player to connect the 2 channels from the bluetooth adapter.

my car audio player has 3 sources which are: AUX , CD , and FM.

I can choose either the CD or AUX

if I choose the AUX like I've done here all I have to do is put the audio player on AUX source.

if I choose the CD then I have to insert an empty CD to the player to make the player goes into CD mode
and the same goes for cassette

in this case I choose to hook my bluetooth adapter to the AUX so whenever I put the source on the player to AUX the bluetooth will connect.

Step 2: Connecting Wires

To find out where ro connect the audio channels wires to the audio player , you have to have the datasheet or the circuit diagram for the player.
usually you can easily find it in google.
I found mine in google and if you cannot find it in google sometimes you can find the channels label on the PCB itself, or you can use an multimeter and knowing the IC model you can find out the channels pins.

each audio source usually has two channels left and right and as I mentioned that I will connect mine to the AUX source, I searched on the data sheet for AUX LCH and RCH.

so now after I found the traces of the channels I will connect my bluetooth adapter channels to the pins on the audio player board.

I solder two wires to the IC pins traces.
BTW each channel from the bluetooth adapter has two wires white and red , the white one is for signal while the red is for ground , so I connected both red wires to the adapter ground and to the audio player case which is ground. and connected the white wires each one to the wire that I soldered to the L and R channels.

last but not least I mounted the bluetooth adapter to the audio player case by double side glue , but first you have to make sure that is there enough space above the player otherwise mount it somewhere else.

now the only wire left is the 12v wire from the bluetooth adapter which I will connect it to the 12v wire of the audio player.