Aftermarket head-unit wiring question

I’ve fitted a Pioneer head-unit to my MK3, it only turns on though if the engine is running!?, is this an issue with my set-up or are they just meant to be like this now - presumably to save draining the battery?


The stations and settings are all remembered after the key-card has been removed and also the head-unit facia removed so it’s not a case of just swapping the red and yellow wires over.


Although the car has a card for a key I still think it has an ‘accessory’ (or whatever the name is) pre-ignition-on setting (like when you turn a traditional key half way but don’t start the engine) as the dashboard lights etc. come on when the card is pushed in the slot.


I’m just trying to get my head around what to do - the yellow wire is thicker therefore must be the switched-live (i.e. the one that draws all the power once the ignition has been turned on) and the red wire is thinner therefore must be the permanently live wire (i.e. the one that constantly draws a little power to keep the head-unit’s settings).


So if I want to be able to use the head-unit without having to turn the engine on do I connect the yellow switched wire to something like the cigarette-lighter live, as I think this comes on when the key-card is pushed in the slot?


I’m also fitting a new amplified DAB/FM roof aerial and it says to run the power for this from something like the cigarette lighter live as apparently the power back from the head-unit through whichever wire it is isn’t powerful enough.


Will I be ok running both the head-unit and aerial from the cigarette lighter? Or are there any other alternatives??


Any help would be greatly appreciated, thanks!

 

Thanks, coincidentally I have since had that thought myself. It’s more regarding the implications of it all.


It looks like my head-unit must know when the engine is running as it only switches on if it is, therefore the switched-live must be wired correctly otherwise the head-unit would work all the time (which is what I would like it to do). So I guess I need to wire both the switched and permanent lives to a permanent live.


I wonder if, because it’s a “high-powered” 4 x 50W unit that it needs the engine to be running for it to work, otherwise perhaps it can’t get enough out of the un-charging battery????


One thing I noticed yesterday is that I couldn’t get the head-unit to turn on at all unless the little ‘box of tricks’ that the steering-column controls plug into was also plugged in, so there must be a switched-live that powers into the box and out again to the head-unit.


If I make everything permanently live I wonder if too many things will be draining down the battery??

 

Thanks Jakg and everyone! Yes I got myself confused there, I checked last night with a multimeter and the thick yellow wire is permanently live, strangely the Connects2 loom adapter that I have doesn't have a switched-live - the input into the Pioneer's switched-live comes from the Connects2 little box which itself is just feed from the permanent live...??

I also found out last night that the car's own switched-live wire (which now just stops at the quadlock connector) and also, for example, the cigarette lighter all become live when you unlock the car.

So if the head-unit is constantly powered by the yellow permanently-live wire how come it only comes on when the engine is running????

 

I’ve just spoken to Connects2 the manufacturer of the loom adapter. Apparently its all correct that the head-unit only works when the car’s engine is running!? - apparently lots of cars are like this nowadays. The head-unit receives an “on” signal through the Can-Bus system (I don’t pretend to know what this is). He said if I could definitely find a switched-live in the car that there was nothing stopping me running a wire from that straight to the switched-live input in the Pioneer loom.


My illumination function doesn’t work either, apparently this is also controlled from the Can-Bus system, he said to first make sure that the orange ‘illumination’ wire in the Connects2 loom becomes live when I switch the car’s lights on, otherwise there may actually be a problem with the little box. Otherwise if I can find an illumination wire somewhere in the car I can tap into that and run it direct to the Pioneer loom.


Does anyone please have a wiring diagram for the car’s quad-lock plug as presumably one of these is the illumination wire – or are there any others I could tap into??

 

Thanks dude!

 

So, just a quick update - It’s all in and working perfectly!!


In the end I bypassed the Can-Bus box thing in the Connects2 loom and created a switched-live from the cigarette lighter, I also needed this for a switched-live to the new amplified DAB/FM aerial I put on the roof. I also bypassed the illumination feed from the Cab-Bus box and took this straight from the car’s loom (thanks RS250!).


So the head-unit and aerial now become live when I unlock the car rather than when the engine is running plus also it dims when I turn the lights on - which for some reason it didn’t before even though the Can-Bus box was sending a live signal when the lights were on?!, likewise the switched-live. Perhaps there is an issue with the Can-Bus box, but regardless it’s all working perfectly now!!