- My model of MX-5 is: _Nc 2012
- I’m based near: Kingston u Thames
- I’m looking for technical help or recommendations on: _ new head unit and power
I have fitted a new Sony head unit to my 2012 power retractable hardtop. I took out the old Bose 6CD multi changer head unit and trying to fit a Sony head unit.
I have brought the proper kit from dynamic sounds setting me back over £100 which I was quite shocked at! Anyway, I wired it all up except for the blue and white wire. My understanding is that this had to power the amp. I put it to a switched power supply, solid blue cable, but the battery was drained after 24 hours.
I use the voltmeter to check if power was going through it or not, and power was not going through it, but the battery was still drained.
I also, in desperation, bought a fuse extender kit and took another supply from the cigarette lighter fuse by the passenger foot well. I wired this all up but the same thing happened again, 24 hours later the battery was flat.
I am totally lost by this and was wondering if anyone else had similar issues whereby they thought they had wired the new head unit into a switched power supply but it did not work at all. HELP!!
If you are not using an amp - the only function for the “switch wire” would be for the amplified aerial.
Power to the head unit should be through 3 main wires.
- EARTH - usually a black wire
- Ignition Live - usually red wire
- Permanent Live - usually yellow wire
If the red and yellow are crossed - the head unit will normally lose settings each time you remove the key. ( It also means the head unit is powered up constantly )
Not sure if the 2012 wiring changed from the 2006 but this is the connection diagram I used.
Is the original Bose power amp still in the boot behind the passenger seat? It’s meaty and can flatten the battery quite quickly if left alive.
This has its permanent power feed from the ‘Audio’ fuse in the footwell, (F02 Fuse Block)
The Bose power amp is switched on or off by the head unit. see the Y/B and P/B wires in CBRDEANO’s circuit, one of them controls the switching.
When I connected my Pioneer head unit I had no power to the amp (no sound) so I spliced the blue/white cable to the blue as shown. It gave power to the amp and shut down the unit when the ignition was fully off as it should do 
Forgive the scotchlock, I replaced this at a later date when found some shrink wrap and bullet connectors.
This is my next move I think. Super helpful. Will
Do this tomorrow. Fingers crossed!
These might also help.
Your switch wire on the head unit needs to go to two places on the car connector.
Pin 1H to power the aerial
Pin 1J to switch on the amp
Super helpful. Thank you. Tackling this tomorrow and will report back.
Yes! This worked. Did the blue to blue and white. Soldered it up and works a treat. Thanks everyone
Argghhhhhhh.
Head unit worked … but despite charging the battery overnight, it was flat this morning. Feels like something could be powering the amp? Any ideas???
How I do I access the amp? I have a PRHT.
Turns out that the battery was knackered. Bought a new one on weekend and problem solved - at last! Thanks all for help.
Have done that myself.
Chased my tail trying to work out what I did wrong after working on the car.
Only to find you did nothing wrong - it was a simple failure of a part.
