Another head unit replacement (2011 Sport Tech bose to Sony DDIN)

I know this topic has been covered a few times, but I wanted to put my experiences down, in case I uncovered any useful info…


I recently replaced the CD player head unit in my 2011 Sport Tech, with a DDIN unit.  This was mostly for navigation purposes, but I also wanted Bluetooth audio.

The new head unit I chose had preamp outputs, so I could properly interface with the Bose amplifier.  I also wanted to make sure that nothing I did required reverse-engineering later, if I pop the original head unit back in.  So, no modifications to the original Mazda wiring.


Parts used:


Step 1: remove existing radio.

For this, I followed all the standard guidance.  For the 3.5/mk3/NC model, to remove the radio and corresponding fascia there are four important steps:

i. Remove the centre console (by which I mean the trim which runs between the seats, housing the cup holder/storage tray, window switches, etc):  1 screw in central cup holder and 2 under the pop-off panel at the rear of the console.

ii. Remove the footwell side panels (by which I mean the trim which extends from the centre console into the footwells on both sides:  1 screw each, revealed when centre is console removed.

iii. Remove the trim under the steering column (pops off).

iv. Remove the radio fascia (includes the radio and A/C controls): 2 screws, plus hidden security bolt which can only be accessed from in the drivers-side footwell, aside the steering column.

    • Note: the cables behind the radio had very little slack in them.

At this point, you will observe that the stock head unit has one large multi-way connector, plus the aerial.  Remove these and also the connector for the A/C controls.


Step 2: Prepare wiring for new head unit:

I had to do some research and take some continuity measurements to fully understand how the power amp is wired.  It’s pretty straightforward actually: 4 pairs of wires go from the head unit to the power amp, plus one extra wire sends a signal to turn the power amp on when the head unit is powered (amp control).  Any other connections to the power amp are not related to the head unit.  My finished connection diagram is like this (note, this is a modification of an Audi Bose wiring diagram which I found online):

mx5 mk3 NC bose sony wiring diagram


i. Firstly, I prepped the basic power wiring.  The Mazda ISO adaptor separates the power and audio connections from the big multi-way connector.  The smaller black connector is power, while the dark red/brown connector is audio:

mazda iso adaptor

The black connector connects to the matching black connector on the Sony ISO adaptor:

sony iso adaptor

ii. At this point, I checked the Head unit powered up correctly (you need to connect the Sony adaptor to the head unit).

iii. Audio wiring:

    • As previously mentioned, I decided to use the preamp outputs on the new head unit and wire them into the power amp.  Some other guides to this have made use of a little adaptor which allows you to use the speaker outputs of the head unit, but I don't personally like that idea extra electronics is normally a bad idea with audio.  YMMV, naturally.
    • I took some standard Phono audio cables and chopped a short section off them.  Then I stripped the wire ends and terminated them into a screw-terminal 'choc' block.  Then, I chopped the red connector off the Mazda ISO adaptor and connected the wires to the terminal block, ensuring the channels were wired correctly (Right Rear, Left Rear, Right Front, Left Front).
      • The nice thing here is that the ISO adaptor uses standard wire colours, which makes this job much easier than understanding Mazda's wiring loom (colours required: Purple, Purple/Blk, Green, Green/Blk, Grey, Grey/Blk, White, White/Blk):
      • ISO wiring colours 
    • At this point, I noticed that the Mazda ISO adaptor didn't have a connection for the amp control ("remote turn on"), only the antenna power.  Antenna power is for a motorised extending antenna, which my car doesn't have.  So, I swapped the pin over in the connector, from loaction 1H to 1J:
    •   mx5 mk3 NC audio connectors
    • At this point, I powered the unit on again to check it was all working.  Seems ok.
iv.  On the Sony unit, the steering remote controls have to connect to a 3.5mm jack socket.  As you can see on the above diagram, Mazda connect the steering controls through onto the main connector.  Unfortunately, the Mazda ISO adaptor didn't have any connections for this.  I bodged it:
    • I found that the pins on these patch leads: are exactly the correct size for the Mazda ISO adaptor.  I just needed to remove the black plastic shrouds and locate them in the adaptor (pin locations 1N and 1P).
    • I terminated those into the terminal block.
    • Then, I took a standard 3.5mm stereo lead, chopped one end off and terminated the bare ends into the terminal block, connecting to the patch leads (only requires TIP and SCREEN connected).
    • Again, I powered the unit back on again and 'taught' it the steering controls, via the settings menu.

Step 3: fit the fascia:

Following the instructions that came with the fascia.  The only challenging part was that the ‘wings’ for mounting the radio were far too thick to accommodate the short screws that came with the radio.  I went to a hardware store and bought some longer screws, but I had to cut them down to prevent them penetrating too far into the head unit and affecting the electronics.

You have to swap the A/C controls over to the new fascia, too.  4 screws.

Note: I wouldn’t actually recommend this fascia, as the plastic is fairly poor quality and doesn’t quite match the rest of the dash.  I’m not sure if there are better ones out there.


Step 4: reassemble the trim and centre console:

Nothing tricky here, but do make sure that the window controls are connected and working before you screw the console down (they have a small connector which seems to come out very easily).


Step 5: relax and enjoy the new head unit.

Although, I should note that now it’s proven to work, I will probably now replace the terminal block with some proper connectors (crimp, or other).


I hope this is useful to someone! 


1 Like

I should also add, the Sony head unit I chose actually isn’t really bright enough to use on a sunny day with the top down!  Jury’s out on how usable it is.

That’ll teach me… spent ages looking at all the specs and choosing a unit which was very tidy-looking… but somehow forgot my car was a convertible.  

Great write up, but I really can’t understand why you didn’t just use the connects2 adapter for the Bose amp, apart from saving a few £’s, it’s literally “plug n play”. The adapter has passive components so I would be amazed if any difference could be heard with the audio, especially in such a harsh environment as a convertible sports car

That was my thinking too! Respect to OP for being able to do this work, it’s beyond my capabilities  but the PnP connectors did the job in no time, only thing now though, my Bose amp has given up on me 



Great write up! I’m not sure why you removed the centre console as it’s not required on the NC1, maybe it is on the NC2


I agree with falling_in2_infinity in that the connects2 amp connection is a complete bodge regarding the audio if you have a set of pre outs you can use



With the connects 2 adaptor in place it goes:


Source – preamp – amplifier –  connects2 reducer – amp – speakers


direct from the pre outs:


Source – preamp – amp – speakers


Lifting the output to speaker level then downgrading it back to line level to then lift it back up again to speaker level just seems daft if you don’t have to.



I agree its daft but sonically you wouldn’t notice any difference


I agree its daft but sonically you wouldn’t notice any difference



I might not be able to tell the difference with my ears but I’d feel better doing it properly, Knowing it could be done better and not doing so would bug me 


I’ll be trying this next weekend.

I’ve ordered:

Bluetooth Car Stereo Double Din,DEKNEI OXd8 Pro 7 inch Touch Screen Car Radio with Apple CarPlay&Android Auto, Backup Camera,Car Audio Receiver Support Steering Wheel Control,FM/AM/RDS Radio

It has wireless CarPlay, four pre-outs (I have bose) and comes with a loom terminated at one end with pins at other end to terminate into a Mazda / Din adapter which I’ve also ordered.

A connects2 fascia adapter, and a set of phono cables to butcher.

As my head unit comes with wires off the main loom, I should be able to hack at the Mazda to din cable for the amp power, steering controls etc etc.

I’ll then do as you did and use some kind of terminal block or crimps to get the Phonos out to the power amplifier.

Fingers crossed!

So this guide was super helpful and I fell into a few of the same pitfalls as you. Not helped by the fact the head unit (random Amazon thing) didn’t quite conform to double din standards.

But a little hacking of the fascia adapter and some finessing and it’s in.

I got this one on a random deal on Amazon for £150 and frankly, for the money it is superb.

Has four pre-outs, illumination switching, speed cable input, and utterly flawless CarPlay. It feels like an OEM head unit in its smoothness of operation.

Still to sort steering controls, but waiting on the breadboard cables so I can add the needed pins!