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Discussion Starter · #1 ·
I have a friend who wanted a non factory head unit in her mazda demio 2003, Mazda have done a very good job of integrating the stock head unit/ac/etc into the dash and don't leave any allowance for a non stock head unit (except for the glove compartment above the dash, but who wants a stereo there??).
So I have been about modifying the dash to fit a custom head unit while keeping all a/c and hazard light functionality.

This is the beast we're talking about: (there are some variations which may work as well but untested.



The reason there are no custom brackets available for this car is that there is a large circuit board behind this panel that controls a number of features, there is no way to fit a new head unit in with that circuit board in place. Unfortunately we need to keep that functionality...

To solve this problem what I have done is removed the circuit board, extended the wiring, and placed the circuit board in a less obtrusive location, the buttons/lights for a/c and hazard remain with the panel.
This leaves plenty of room for a single or even double din stereo/dvd player etc.

Here are the two circuit boards removed, you'll see that the hazard button ribbon cable has been cut, a 4 wire cable with plug will be soldered to it and matching plug and wiring soldered to the larger circuit board.
The smaller circuit board plugs into the large board at a 90 degree angle, this will have short wires soldering it to the large board so it can sit flat against the board with double sided foam.



Here is my current progress on modifying the panel:


I'm using a plastic resin to fill gaps, then will sand/prime/paint.
The head unit fits nicely in the original metal bracket (new holes need to be drilled for the screws)

Will update shortly with progress..
 

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Discussion Starter · #2 ·
Instructions to remove the original head unit/panel:



There are two screws under the red dots, pull the dials off and unscrew.
There is an anti-theft 10mm bolt where the green arrow is pointing, use a 10mm socket and 10" extension to remove it.
Remove the storage box where the blue dot is then reach your hand in and behind the stereo, push it forwards and it should slide out easily.
 

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Discussion Starter · #4 ·
Progress...

That was stock! lol havn't finished it yet..
Turns out you need to keep both circuit boards in the car, not just the front one. Lots of wiring/soldering needs to be done.
I highly recommend using the top glove box and the pass through wiring harness or you will be spending a long time on it...

Having said that, I have almost finished and all functions are working, it is a tight fit though.
I will post pictures soon.

If anyone wants the information on the circuit boards here it is:

The ac/defogger/recirculation buttons are based on a resistor network on the front (larger) circuit board, all the control is passed through the small circuit board that is plugged in to the 10 pin? or so plug from the car.
The problem is that the big circuit board gets it's power from the stock stereo circuit board. currently I have not done any testing to determine which pins supply the power etc. There is a chance also that the resistor network is connected to a microcontroller on the large board making it very difficult to design a smaller board to just control the ac/etc but once I get the car back I will use my scope to figure out a simple way to bypass all circuit boards at least for the buttons (LED's might be a bit harder)

I plan on making a small 2" or so circuit/button board that will replace everything behind the dash allowing you to use any aftermarket stereo and keep all functionality with just the two stock plugs from the car
 

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Discussion Starter · #5 ·
Update

I have done some signal testing with my scope on the 10 pin a/c plug and it looks like it uses the can bus.
I am waiting for my sniffer to arrive and I'm building a avr can transceiver to control the buttons/leds
should be about 2 weeks away
 

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i changed my headunit with all th efunctions still working. It was a **** of a job. as mentioned by sealdogfish there is also some electronics in the radio. I also stripped the radio and connected the 3 circuitboards (hazardlight, radio, big one behind the faceplate) with ribbonwire that is being used to connect computer harddrives. This was a **** of a job soldering all the wires. From the radio i removed all the lights and the display to get a flat circuitboard. Now it all sits neatly above the radio.
 

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Any hints on "how" you remove the glove box and that anti theft bolt is not easy on the eye do you blindly put a socket in there or is there a way to make this a little more visible? But thanks for posting this would be lost trying to do this without info :)
 

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OK I figured out that gentle brute force was the answer for the glovebox and helpful previous owner had removed bolt and never put back (makes it harder to find...LOL) anyway bought a cable to provide a 3.5mm jack for ipod connection and plugged it in but no joy...any ideas? I read something about a media plug but not sure what thats about. Even the band expander isnt working and that was installed by previous owner, found when back removed.
 
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