Kevin,

I bought a four-position switch to replace my four-position/four-terminal switch on my Mercury Marine 5.0 MPI’s boat wiring. 

The problem is the new switch has arrived and has six wires. The extra two say 5 and 6 position are for the battery and ignition – as shown in the attached picture.

Should I ignore these and cut the wires off or should I connect them to 1 and 4? 

Do I need a different switch?

Dan

Hi Dan,

This switch will work fine.

Ignore positions 5 and 6. They are internally connected to 1 and 4. You can either cut them off or tape them up.

Kevin

Kevin,

Your site is great!

I recently picked up a three-bank DC Alternator Charger. I am supposed to run this purple lead wire to the ignition switch so that the charger is on while the big motor is on.

The crude photo attached is all the instructions I have. The paper says the purple wire must be connected to ignition circuit. Reviews on installing thing range from “super easy” to “needed a marine technician to install”. I sure don’t want to mess something up.

I also attached a very crude picture of my console. The red harness is where my ignition connects at. I see the purple wire there. Do I simply have to attach my purple lead wire to the existing wire?

Chad

Hi Chad,

You are correct. The charger connects to the purple lead on the back of your key switch.

I would install an in-line fuse at the key switch end of this new purple wire with a maximum rating of 5 amps. The fuse protecting the key switch will protect the boat wiring, but this additional fuse will blow first if you have a fault in the charger or this new purple wire.

Happy wiring,

Kevin

Dear Kevin,

I am currently beginning my first boat wiring project, a total rewire of a small Owens cruiser from the late ’60s.

Here’s my problem:

The old wiring runs behind the original paneling and headliner. I could try dismantling everything to remove and replace the wires, but am concerned about damaging any of the woodwork. It’s old. It’s gorgeous. It would be a bitch to replace.

I don’t mind leaving the old wiring in place and just running a new harness, but that still leaves the problem of installing the new wires without causing any damage.

Any ideas?

RP

Dear Ron,

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Call now to order. The toll free number is 877-277-3665. Operators are standing by. That’s 877-APR-FOOL.

Kevin.

Hi Kevin,

Lots of good help on your site.

I’m restoring a ’77 Century Arabian.

I made a new dash and was very careful to replace all the boat wiring where it was before. Nevertheless, the moment of truth came with a turn of the key and…the fuse blew. I replaced it with a 15A. Blew that one. Same the third time around with a 20A.

Hookups are correct with three posts on the back of the switch IGN, BAT, and SOL according to your other emails. I wonder if I am not going to ground somewhere back in the engine.

My question is – where do I start?

Thanks,

Joe

Hi Joe,

The ignition wire (purple) provides power to the following:

• Gauges
• Coil – through ignition interrupter
• Alternator Excite

I would eliminate one system at a time to find your problem.

The main area I would focus on is the gauge wiring. The terminals are close together and even though all the wires are connected to the correct terminals, you may have a purple (ignition power) touching an black (ground).

Let me know how this turns out. Please send me pictures of your new panel.

Kevin