Troubleshooting Engine Kill Switch / Breaker

Hi Everyone,

I'm looking for some advice on figuring out why my engine kill switch / breaker is tripping. Here's the scoop:

The master engine breaker/kill switch trips when the boat is running. It seems to trip related to engine RPM (sorry my tac isn't working so can't tell you the specific RPM) but it typically trips around 15-20 mph. I run the boat in salt (with plenty of rinsing and flushing) and fresh.

Upon initial troubleshooting I found the wire harness plug had some pretty nasty corrosion on two of the plugs. I suspect the breaker is tripping because of a current spike due to the corroded plugs. However, what I'm not sure about is if the plug corrosion is the primary cause of the current spike, or if the plug is corroding because of an upstream electrical issue.

My boat is in storage right now so writing this off memory and limited pictures. I'm pretty sure the corroded plug is on the alternator side of the pigtail. I'm also pretty sure the two corroded plugs lead back to the alternator.

How do I check the current coming from the alternator? What range should I be seeing?

Lastly. For replacing the plug I plan on buying this pigtail (SkiDim Pigtail),cutting it and splicing in the new plugs with waterproof marine connectors. I realize it would be better to replace the entire harness but that's a lot of work just to replace the plug. Thoughts?

Looking at your picture I would say your problem is the melted plug which was probably cause by the corrosion.
Just a guess.

I would snip those 4 wires, strip them back and use a wire cap connector for that wire gauge and reconnect them back together to temporarily see if the plug was the problem. Then repair it more permanently later.

I use a multimeter daily in my business. You should see 14+ volts across your battery above idle. If you see way more than that your voltage regulator is over taxing your alternator. There's nothing wrong with using a wire nut for a temp repair to see if the problem subsides. You could use a solderless crimp connector with shrink wrap like those used in well connections, but you will not have the luxury of separation at a later date .

Cont...

I'm sure the plug would be useful when the engine needs to be completely removed (or installed at the factory). If that's the main purpose I can live with having to snip wires in that case and eliminating contact points for salt air/moisture to get into.