Fishing Boat Wiring Solutions

Kevin Hannula answers your questions about fishing boat wiring and marine electrical.

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Ignition Issues


I had to get a new ignition switch after hubby broke the old one. Then he didn’t tape and write on the old boat wiring what they went to.

Can you give me the colors and letters that go together? The new one that he bought has the letters, S, I, C, M, B, M…I’m not even sure he bought the right one!

Thanks for any help you can give me.Ignition switch


Hi Tami,

He did buy the correct key switch.

Here are the colors and letters.

  • S – start – yellow/red
  • I – ignition – purple
  • C – choke – purple/white
  • M – magneto – black
  • B – battery – red or red/purple
  • M – magneto ground – black/yellow

Happy boat wiring,


Thanks, Kevin.

The engine now turns over but the bilge, lights, etc. don’t work.

My old switch had S,C,A,M,B, and M, but no “I”…and hubby didn’t mark the wires. The switch even looks different. I’ve included a picture of the new switch with wires.

Please help! I love my boat and hubby wants to get rid of it, so he’s not doing much to fix it.



The bilge pump, navigation lights, etc are either powered by a separate lead that has nothing to do with the ignition switch or an additional wire that would connect with the purple wire.

Check to see how the boat switch panel gets power and also check the ground. If all components quit, it is either the power or the ground for the accessories.



I forgot to mention that the navigation lights, etc were working before I switched the wires to make the engine run – and it was all working before hubby broke the switch itself.

I just feel that something is either not connected correctly or we have the wrong switch. Did I wire it correctly? I was told somewhere else that the switch I have is for an I/O motor. Could that make a difference? Would switching the M and the MA make the difference?

Thank you so much for your help.



An I/O switch will not have a choke, a mag, nor a mag ground terminal. You do have the correct switch.

Switching the M and MA will not make a difference. When you turn the key switch off, the M and MA posts are connected together internally to make the engine shut down.

Since all of your accessories have quit, there must me a wire left off either on the battery or the key switch. Is there an in-line fuse at the battery on a smaller wire?



I fixed it!!! Yipeeeee….Thanks so much for all of your help!

My next project is to see why the tilt/trim doesn’t always want to work…..and then to learn to back the boat…that’s on my bucket list for this summer.

Thanks again…you’ve been a blessing!


VSR OK with all engines?

Hi Kevin,

I’m redoing my boat wiring and considering adding one of the EzAcDc Smart Battery Switches.

Do these setups work with all outboards or do some engines have a problem with the automatic switching?Force outboard



Hi Pat,

The Smart Battery Switches from our partners at EzAcDc will work with all outboards, but some work better than others.

If you have an outboard engine with a small alternator (less than 15 amps) and you have large DC loads (large stereo amplifier, trolling motors, etc) connected to your house battery, the system will cycle on and off every few seconds because your alternator cannot keep up with the demands of your system.

If you turn off your loads, the alternator can eventually keep up and charge the system.

Most newer, larger outboard engines have 40+ amp alternators and the system works great.

Hope this helps,


Sticky: Fishing Boat Wiring Questions?

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