Introduction: Hack in a Bluetooth Connection to Your Car Stereo for $10

Here’s how to add a Bluetooth audio connection to any car
stereo for under $10.

Step 1: Remove and Disassemble the Radio

I’ll be demonstrating this on my 2004 Toyota Camry with a basic CD AM/FM radio.

The first thing to do is remove the stereo.

Remove a bunch of screws from the outside of the casing to
reveal the motherboard.

Step 2: The Motherboard

There’s three main chips, the one on the bottom controls the
I/O interface, there’s one under the heatsink, and the one at the top right controls the audio signal – that’s the one we want to hack into.

Step 3: Finding the Audio Input Lines

According to the pinout diagram, we need to find the left signal and right signal. In my case, I’m going to tap into the CD input lines, since its an analog audio signal. I’ve traced these from the CD board header, all the way thru to the chip. Here are the potential soldering points.

a pinout I found online of the same chip U102 TA2123AF, detailing pins 51 as the right and pin 62 as the left audio signal for the CD.

Step 4: Components Needed for the Hack

You’ll need three main components:

1. A 3.5mm audio cable to solder to the motherboard

2. A Bluetooth receiver to convert to the 3.5mm hack

3. 12V to 5V USB power inverter

All can be had for less than $10 depending on the quality of components you choose from eBay or Amazon or the like.

Step 5: Solder the AUX Input to the Stereo Chip

Got my aux cable wired in. At this point you can just leave the radio with just an AUX input, but for you iPhone users without a 3.5mm jack out there, read on for the Bluetooth hack.

Step 6: Closing Up the Radio

Closing things back up in the radio.

I opted to wire the Bluetooth module outside the radio. I tried tapping into the power lines coming in the radio and almost fried it…so I’d rather play it safe!

Step 7: Powering the Bluetooth Module

Here I tapped into the 12V lines going into the cigarette lighter. Mind the messy wiring, this was just a prototype!

Step 8: Enjoy Your Bluetooth Connection

Finally once everything is back together, you can connect to Bluetooth on your phone. You’ll need a CD with a silent track that will trick the radio into reading from the CD input. You can download and burn this CD yourself.

And that’s pretty much it, you can enjoy CD stereo sound through Bluetooth connectivity on your phone for less than $10!