Stereo wire to acc switch. Help.

[evan.wildeman1]

Want to wire my Max stereo head unit to a spare acc switch and read lots of forums but still unclear of what wire to take off the ignition and relocate to the acc switch. Attached picture of the ignition and acc switch. https://uploads.tapatalk-cdn.com/20190414/60bec1d255d956c8fdcc90c9a9081c57.jpghttps://uploads.tapatalk-cdn.com/20190414/b2a42b6b721c3a4277dddd0b71555c02.jpg

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[MLA]

If its a traditional key switch, it should be labeled ACC. Regardless, break out the volt meter and find the terminal thats the only one with battery voltage with the key in ACC position.

[z28ke]

Figure out which wire from the switch is “hot” when the switch is turned on, and you want to cut/splice that to the yellow wire (power) on the back of the fusion head unit.

[z28ke]

I think it’ll be the white wire in the 2nd pic. Cut that wire, and the yellow wire on the back of the head unit, then splice in a wire connecting the white wire coming out of the switch to the yellow going into the head unit.

No need to mess around with the ignition switch to do this. You take that out of the picture when you cut the yellow wire at the head unit (since it’s coming from the switch anyway). Be sure to put some electrical tape (I prefer liquid electrical tape for something like this) over the cut end of the wire since it’ll be hot when the ignition is on.

[evan.wildeman1]

Seems straight forward enough. Thanks for the reply!

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[MLA]

Figure out which wire from the switch is “hot” when the switch is turned on, and you want to cut/splice that to the yellow wire (power) on the back of the fusion head unit.

Hate to disagree. With the key switch in the on, or RUN position, there will be more terminals with battery voltage, then just the head unit's IGN. The correct terminal will only have voltage in ACC.

2nd, the head unit yellow is the constant B+, not the IGN turn-on.

[z28ke]

Hate to disagree. With the key switch in the on, or RUN position, there will be more terminals with battery voltage, then just the head unit's IGN. The correct terminal will only have voltage in ACC.

2nd, the head unit yellow is the constant B+, not the IGN turn-on.

No worries MLA, It’s been a while since I wired mine so I looked up the wiring diagram before posting. I didn’t see a remote wire (except for the amp turn on) like in normal car head units?

What you wrote about the ignition switch is why I wouldn’t mess with the wiring there. It’s turning on multiple circuits.

https://uploads.tapatalk-cdn.com/20190414/a25ca172ded399482f2175fcd2828369.jpg

[csm]

If yours is a 2019 (can’t speak for 2018), all of the unused accessory switches run power wires that have empty connections. If you get under the dash from the bow side, you can find them zip tied in bundles of other wires. I found one labeled “docking lights” with an empty female spade connector. This turned out to be run from the accessory 4 switch. I run my power to the head unit from that spade connector now.

[evan.wildeman1]

Yes my accessory 4 is also docking lights and was the one I was going to use for power.

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[MLA]

The OP did not state what year boat. I presumed he has the MA-RA205 head, which does have the red IGN.

As to messing with the switch. Where he interrupts the circuit, is irrelevant to finding the correct wire with a volt meter. Once he knows the wire color, which was his question, he can trace it to where ever, or take it right off the switch. If he uses a circuit hats "hot" when the switch is ON, good chance its the wrong one.

[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?

[MLA]

Only one switched stereo wire from the key switch. Theres a little mechanical magic going on inside the switch that makes the ACC terminal "hot" in both the ACC and RUN position.

You may not see a tag on the wire, but rather the terminal is labeled.

[996scott]

ok, good to know. Thanks again for the help. One last question if you don't mind. Is there a trick to getting the wire (pin) out of the terminal or should i just cut the wire?

[MLA]

If the back of the key switch is sealed, with no serviceable terminals, then you may trace the ACC wire to see if it goes through a fuse. This would be a good spot to separate it and divert it to the rocker switch.

[996scott]

Thanks again MLA, I got it done. FYI for anyone else, I was able to see the red wire coming out of the harness on the back of the stereo. I followed it down a little ways and found that it had a label saying 12V on it. Along with 3 other wires it went into another white wiring harness. I unplugged the white harness and removed the red 12v wire from it. With the red wire taken out of the harness and the harness plugged back in I confirmed there was no power to the stereo. I then found an extra wire from one of the empty ACC switches that was just bundled up and connected the two together. Works perfect as when the toggle switch is in the on position.

[sandm]

996- congrats. nothing better than a job well done...

and frankly the best mod you can do to any boat out there.

[996scott]

Thanks sandm, considering my lack of knowledge when it comes to electronics this was no small miracle. Yea, it is always a great feeling getting something figured out and doing it yourself.

[NCSUmoombaMAX]

I'm a little confused... If the key is turned to the left to the "ACC" position, doesn't this accomplish the same thing? Why would the audio system need to be wired to it's own separate switch?

[MLA]

I'm a little confused... If the key is turned to the left to the "ACC" position, doesn't this accomplish the same thing? Why would the audio system need to be wired to it's own separate switch?

When you go from the RUN to ACC position and then from the ACC to the CRANK/RUN positions, there is an interruption in the switched 12V turn-on signal to the head unit. So it shuts off and back on. This can wreak havoc with blue tooth. Sometimes its a short pause in the music, sometimes, you have to re-pair the phone.

Replacing the ignition key switch with a manual rocker switch keeps the head unit turned on, regardless of the position of the key.

[996scott]

If the key is turned from "on" to the "acc" position the stereo will turn off and then have to reboot again which takes a little bit of time. It's not bad but just kind of a nuance. If the stereo is hard wired then it always stays on regardless if you are turning the boat on or off.

[996scott]

woops, didn't see MLA had responded.

[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]

https://uploads.tapatalk-cdn.com/20220507/51fcc20578d5c7b951c8713562429e2f.jpg

[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]

MLA, if this is the case then should I reverse my red and yellow from the HU? In other words, make the yellow the “switched” wire at the rocker?

[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.

[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.

[WildH]

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.

Yeah I thought about the other coponents possibly being on , but wasn't really worried since they would be on with IGN key anyway which is my alternative. Was thinking the power would be fused for each component but I suppose if I'm sort of back feeding it I may be bypassing any fuses?

Either way my hard work is done and fixing should be easy. Would just need to cut the red power wire at the harness.

[shawnrw]

Has anybody considered making this change at the breaker panel to maintain a constant 12 volt source to the head unit?

I'm getting ready to install a RA-770 HU and the yellow power line requires a 15 amp fuse/breaker. I would like to continue to utilize the 15 amp stereo breaker on the panel as it's currently 15 amps for the stock HU. My hope is an adjustment can be made at the harness or panel level to accomplish this.

Thx

[MLA]

Has anybody considered making this change at the breaker panel to maintain a constant 12 volt source to the head unit?

I'm getting ready to install a RA-770 HU and the yellow power line requires a 15 amp fuse/breaker. I would like to continue to utilize the 15 amp stereo breaker on the panel as it's currently 15 amps for the stock HU. My hope is an adjustment can be made at the harness or panel level to accomplish this.

Thx

What year is your boat? Are you sure the 15S stereo breaker is not already a constant 12V when the main battery switch is on? With that said, if your boat external amps, i would not want to use that helm panel breaker anyway. Easy path to unwanted noise.

[shawnrw]

I have a 2022 Moomba Makai.

I'm pretty sure the 12-volt stereo line is not a constant 12 volts as the radio turns off during starting. The RA70 HU only has one 12-volt line, whereas the newer/older models (RA770) have a yellow and red line, one for constant 12-volt and the other to act as a turnon signal. I agree with the noise concern, but I wanted to keep it as close to stock as possible, given I don't have noise issues now.

[MLA]

That 12V source to the breaker is probably seeing a voltage dip due to the engine load. Cranking the engine has nothing to do with it being a constant 12V on the boat side of the main switch. Again, have you tested it for voltage?

Nowhere am I advocating to change any (yet, lol), simply asking if you measured for voltage. Those breaker panels are supplied once the main battery switch is turned on, There is no key, rocker or toggle that supplies them. Their input terminal is often times, tied to a BUSS bar, so all the breakers have 12V at the same time.

[shawnrw]

I believe I mispoke a little, by starting I meant when moving the key switch from run/off/acc. It appears the rocker switches are hot regardless of the key position, while the radio is hot only in acc or run and the wake computer only works in run. I'm not sure if this power separation is controlled via the breaker panel or at the harness level.

It's prob. best to just wire the radio direct to the panel, but I would like to figure out the power system for the key in the run position. I'm installing thrusters and would like the controller to only power on when the key is in the run position.

[HFarr]

Update us on that thruster install when it happens!

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[MLA]

Im pretty confident, that the 15A stereo breaker is not wired through the ignition key switch. In reality, wiring the 2-wire RA70 to the key switch, was a poor decision.

Moving forward, your new RA670 is a 3-wire harness. Black ground, yellow 12V B+ and red switched IGN. So, as ive said, the 15A breaker likely has 12V when the battery switch is on, and this is where the 670's yellow would terminate. The red would terminate the to key switch's ACC, if thats how you want it to work.

[shawnrw]

The moomba boats with the RA70 head unit only have 1 power wire with no ignition signal wire as most head units have. It’s wired where the power wire is only hot with the key on ACC or Run, checked with a voltmeter. It's odd, but the breaker is not getting power unless the switch is in the positions mentioned above. Curious on what their engineering reason was for wiring it this way.

[Holdmybeer]

The moomba boats with the RA70 head unit only have 1 power wire with no ignition signal wire as most head units have. It’s wired where the power wire is only hot with the key on ACC or Run, checked with a voltmeter. It's odd, but the breaker is not getting power unless the switch is in the positions mentioned above. Curious on what their engineering reason was for wiring it this way.

This might be true for newer boats but my 2015 was not. The yellow and red were connected via factory harness and landed on switched power from the key.

I have since separated them so yellow is constant power and red works off an aux switch that wasn't being used. This way I can listen to the radio without the key yet all power is removed by the main battery switch. Fusion recommended this so A) it doesn't keep surging the new stereo (I went through 2 if them in a month) and B) you only power the music while floating and nothing else has to be on. The radio also doesn't surge while starting or turning the key from ACC thru Off to RUN. Again MLA is correct the 15a requirement is on the yellow wire and should be from a good source (i.e. radio fuse) but red draws minimal current and is wired to a 5A factory toggle switch.

[shawnrw]

Holdmybeer,

The boats are wired the same as you suggest, I prob. just didn't do a great job explaining it :-).

I was hoping I could make the change at the panel to move the radio from switched power to constant maintaining the stock harness setup, but I'm not sure where the switching happens, etc. It's likely far easier to just to wire direct at this point, likely better for noise as well.

[Holdmybeer]

If you crawl under the dash the factory harness is just a couple of white connectors.

The Fusion radio harness is wired to 1 of those. Follow the red and yellow wires directly from the back of the radio until they join together. Most likely this happens where it meets the white connector skiers installs. Mine did. From there you can modify the harness to the way you want it.

If you just don't want to hurt a brand new boat (I get that), the connectors can be purchased online and you can wire a new harness and just unplug the factory unit and plug your new one in. The harnesses I'm referring to has the speaker wires and power wires separated in different connectors.

If you ever want it to be "factory" again just plug the harnesses back together and remove the 1 you installed and you didn't cut any factory wires.