Intro: Hack a Gm Radio Under 40$
In this I'able I will detail how to install a Bluetooth headset directly into your radio head unit to remote control your head unit from your phone.
STOP, PLAY, Volume up, and Down, direcly through BT, on your wireless device.
Now I have a old 2004 GM Colorado first Generation, my radio is a simple CD player/Radio. In order to put Aux radio jack into this radio GM requires you purchase an 80$ encoder dongle. This IS NOT Needed.
Matter of fact this was so simple I was shocked.
Now this should be do able on any radio, but this method details on GM radios.
As for operation, simply turn the BT unit on, it will Directly override the radio signal. for best results turn the radio volume down, and use the remote blue tooth connection to volume up and down.
I use this everyday with my droid 4 to play audio books from my audible account.
Enjoy, I hope this works if you have any questions leave a comment.
Step 1: MAT'S and TOOLS Required.
This is a list of tools and materials you will need.
1. Soldering tools.
3. small socket set.
4. Magnifying devices
5. 1/2 inch drill bit, to install switch.
6. Drill (not pictured.)
1. small Bluetooth headset A2dp compatible, or Stereo ready. 24$ Amazon HM3500
2. mad soldiering skills.
3. Roll of wire. $5 Radio shack
4. Two Types of switch, 1 Momentary and one on/off toggle. - $7 radio shack
5. a scrap wireless car charger.
7. Radio. - free use your old one
8. Electrical tape. - barrow some
9. 1x headphone jack stereo ready. - 2.29 Radio shack
Chip diagram for radio.
Step 2: Removing Your Radio.
My radio is a 2004 GM RDS/RD air first Gen digital radio.
It was held in by three bolts, after removing the faceplate; which was held in by three friction clips I simply slipped it free from the chassi and removed the two connector plugs, Will be 2 one for radio power and speakers and a second for your antenna.
Step 3: Breaking Down Your Radio.
on my radio there was two snap on plates that covered the bottom and the top, simply remove these. after the top cover is removed there are like twelve small clips which held the face plate on.
Step 4: Viewing Your Radios Brain.
Essentially you will be creating a direct speaker input for your Bluetooth headset. Using a small headphone jack. Here is how it is done.
Now my radio uses a Saa7706h Digital signal processor, I google my chip and pulled the PDF data sheets.
There are 4 pinouts you are looking for FLV, FRV, RLV, and RRV These pins are chips output pins and led directly to the amplifier, but after the volume controller.
I wired my connections directly to FLV, and FRV, using a small 3 pin stereo head jack, I used a Ground located on the side of the radios board mount.
To get some perspective on your chip the number one pin should always be located near the dimple on the chip.
Step 5: Installing Your BT Headset.
1. First step is to take a small screw driver and pry the BT head unit apart. inside there will be a few controls, Volume, and Sync. your only concerned with the SYNC button..
2. remove the old battery, and soldier your USB car charger directly to the old battery terminals.
3. Flipp the unit back over and soldier wires directly to the sync button, The button should be covered with a foil shield, you will need to pry this away. The button once exposed should be divided into a positive and negitive terminal. Soldier a wire to each terminal, leave enough wire to trail outside of your radios housing. ANOTHER CAUTION NOTE. SYNC YOUR BT WITH A DEVICE BEFORE YOU REMOVE THIS BUTTON, There is a change you can destroy the button trying to soldier to these terminals.
Leave enough wires trailing outside of your radio so you can affix extensions as needed.
Powering the BT Headset.
I wired a secondary cup connector directly to my power point, then pluged the usb charger into that. this way I can fully conceal the wiring inside my dash.
I used a on off toggle to power on/off my BT headset.
Wiring the Snyc button so you can resync to new phones after you enclose your head set. into the radio.
I simply used a off/mom switch for this.
afterwards install your radio, make your final solder connections, and walla... SYNC BT RADIO.