Stereo wire to acc switch. Help.

[996scott]

reviving an old thread. I want to do the same and wire the stereo to an extra switch to keep it on and not have it cut out every time i turn the engine off. From the picture that the op posted of the back of the ignition switch, which wire is it that goes to the back of the head unit for power? (sorry i'm not much of an electrician and don't have a volt meter). I would want to cut this wire ( or take it out of the back of the plug) and then connect it to the wire that comes from the extra switch which would be the white wire in the 2nd picture. Is that correct?

[MLA]

@996scott,

If your 2021 uses a traditional key style ignition, then the terminal should labeled ACC. Usually, its a red wire. Even then, I always like to verify with a meter, that the wire has B+ in the ACC and RUN position, then after removing the wire, make sure the head no longer powers up.

Get a $30 meter from the auto parts store or harbor freight. its worth its weight in gold.

Yes, once you have the correct wire off the key switch, simply wire it to the switched B+ output of a spare/unused rocker. If its a typical Carling style rocker, you can swap the actuator to a custom one labeled to indicate music.

[996scott]

MLA, thanks for the response. Yes it is a traditional key style ignition but i didn't see anything of the wires coming out of the back that were labeled ACC.

Sorry if these are dumb questions but when it come to electrical i am as dumb as they come... So it the radio powers up when the key is in the run position AND the ACC position, does that mean that there are 2 wires coming out of the back of the ignition switch that go to the radio and they both supply power to the radio dependent on which position the key is in?

[BigOrange]

Revive this thread. Since my original fusion HU died I’m installing the ra-210 and want to go ahead and wire directly to an ACC SWITCH to get it off the ignition interruption problem. I’m butt connecting the harness I cut from boat to new stereo but see old HU ignition red and power yellow are both together in the white harness (see pic). In this case I need to remove or ignore the red on this harness and take the new HU red to the ACC SWITCH, correct??

[BigOrange]

[MLA]

The head unit's red wire (not the boat harness red) needs to go your switched source. The head unit's yellow can connect to the boat harness yellow as it was with the original unit.

[BigOrange]

Ok, need some more help. I finished wiring it up tonight for a trial before getting everything tidy. It all works as it should — but the HU still loses power with key in off position. With key in ACC or Run, it works fine and using the ACC rocker switch I wired to will still cut power, but just no power when key in off position. I even confirmed with meter that the ACC rocker switch had 12v power with key off. With key off if I toggle the switch the indicator light will come on the rocker switch, but the HU does not power up?

[MLA]

With the key switch ON or in ACC, put your meter on the yellow. I bet you have 12V. Now turn the key off, I bet 12V goes away.

[BigOrange]

With the key switch ON or in ACC, put your meter on the yellow. I bet you have 12V. Now turn the key off, I bet 12V goes away.

Just checked and this is true.

[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.