Stereo wire to acc switch. Help.

[Holdmybeer]

To make this work....
1) connect everything normally and skip the switch.
2) once working as installed, confirm 12v at rocker switch input with key off
3) on rocker switch output, connect to both yellow and red.
*both wires need 12v for the radio to work.
4) add fuse rated at 10A max to rocker switch input - between power source and switch.

Test..... rocker off key off = no music
Rocker off key on or acc = music.
Rocker on key off = music
Key on or acc music...... switch rocker to on...... key to off music should continue.

Done....... disclaimer.... I am not saying this is a good idea. 2 power sources could cause electrical issues. Back feeding power to other sources or multiple ground loops can cause shorts and in some cases resistive loads become heaters and can cause fire. Leaving the rocker switch on 100% WILL KILL YOUR BATTERY. Your amps remote turn on wire is powered through the radio. All of this will be powered.

[MLA]

3) on rocker switch output, connect to both yellow and red.

Two potential issues with this. 1) this would invite ground loop noise. 2) good chance there will be a turn on/off pop/thump.

Just checked and this is true.

So now you need to find a proper constant (when the main battery switch is on) 12V for the head unit yellow. The best source, is right from the amps' 12V BUS bar source.

[BigOrange]

Well I thought the bad luck was supposed to be yesterday.

I had a spare wire from original install from the amp rack area. So, I used it direct from bus bar to power the HU yellow. All good - checked and everything working properly.

Then, went to mount everything back up tidy - HU, Exile ZLD, and zip tie wires. Now - amps and ZLD won’t trigger on when HU comes on. I don’t get it.

[MLA]

Check battery voltage. The amps and head unit could be drawing off different batteries now. Check the splice(s) for the turn-on wire to the amps and zld

[WildH]

I haven't tried this, but couldn't you just run a wire from an ACC switch and splice in on the power for the HU?

Then the HU would work normal if the ACC switch is off and then stay on when the ACC switch is on. Would this possibly cause noise? And/or would it still cut out when engine is cranking over?

[BigOrange]

Just to update. Last weekend I found what turned out to be just a loose connection on the new fusion wiring harness that carried the power and amp remote turn on (among others) where it plugs into the back of the HU. Seems funny that it would get one connection but not the others. But, I had

1) everything working
2) amp turn on not working
3) nothing working - no power
4) back to all good.

It must be real finicky. My ZLD is mounted right below HU so getting my hands to the back of the HU is tough.

Running yellow power wire all the way back to bus bar was the trick for the ACC switch to function as intended.

[WildH]

Just an update if anyone is curious. I wired this today by taking a 12v + from an open ACC toggle switch and spliced into the power lead on the Fusion HU. I left the HU power intact to the factory harness so it still functions with the ignition key and ACC switch just acts like an override to keep it on. Works like a champ.

[MLA]

If im reading it correctly, you are now supplying 12V into the IGN switch when its off, from the ACC rocker switch, when its on.

I would suggest you use either the IGN key circuit or the ACC switch circuit, not both.

[WildH]

If im reading it correctly, you are now supplying 12V into the IGN switch when its off, from the ACC rocker switch, when its on.

I would suggest you use either the IGN key circuit or the ACC switch circuit, not both.

I took the 12v from the empty toggle and tapped it on the 12v HU power line and left the 12v HU power line in tact to the factory harness. So yes I would suppose that when the toggle is on, a 12v is running back to the IGN. But this is no different than the IGN switch being in ACC or RUN position.

Why do you feel this would this be a problem? All other boat components operate as they should with the IGN in the off position. Only the stereo continues to play. The only thing I saw as a side effect was that the LED on the toggle turns when the IGN key is turned on which makes sense.

[Holdmybeer]

MLA suggestion is not a bad one. Backfiring the 12v to the IGN won't hurt anything but it will power other devices you do not know is running and drain the battery quicker. Having 2 power sources at the same time running from different size fuses/breakers could cause a problem if the radio becomes shorted to ground. The wires designed for 10A radio are now supplied more and wires can melt. Again, being dramatic but things happen and don't want to see anything happen that could be corrected.

Running the yellow radio wire to constant 12v and using the switch to power the red radio wire will work better. I know the switch would have to be on to power the radio and could easily be left on and drain batteries. However, if you turn the batter switch off regularly then this a moot point also.