Engine Control Panel J/42 out?

[Dennis Boyd]

Hi guys.

We got some water on Jaywalker,  long story, good for a beer conversation.    But bottom line it killed 1/2 of my Yanmar Engine control panel.    The engine starts, runs fine, charges the batteries, and shuts down.

I don't have engine alarms, horn, tach, oil or water temp.   The in panel fuse is blown and blowns when replaced?

Any tips on what may have shorted out or blown?   And where I can look to find it?

thanks, 

Dennis

Jaywalker 

J/42 #6

[Todd Stevens]

I haven’t looked closely at the panel, but generally (on engines that I have known) that stuff is on a purple wire coming out of the switch.  Usually daisy-chained so if one thing goes bad, everything downstream fails as well.  Just trace the circuit and you’ll find the problem.  

I have never liked the idea of panel wiring hanging out into a lazarette or busy locker.  On my last boat, I built a backshell to contain it.  Haven’t got around to it on the J.  I also rewired it to eliminate the daisy-chain. Everything wired independently to a terminal strip. That little project ended up taking an unreasonable amount of labor and terminals. No wonder they use the daisy chain.  

Sent from my iPad

On Jun 12, 2026, at 11:33, Dennis Boyd <dennis....@gmail.com> wrote:

Hi guys.

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[Tom Keffer]

All I did was tape a ziplock bag over the back. 18 years later, it's still working fine.

To view this discussion visit https://groups.google.com/d/msgid/j4x-owners-group/1759F864-0576-485C-8EE3-DED110E3D077%40me.com.

[Dennis Boyd]

Todd, 

Thanks.    I  will look at that.   If it's any help.    Water came from bilge up and not panel getting wet.    Bilge pump failed (since been replaced) locked and blew fuse, while sitting in slip.    So I am thinking it's somewhere in harness going to panel.

I got an engine guy coming, but it might end of next week.   Just hoping someone on the forum has had a similar experience. 

Dennis

[Dennis Boyd]

I like the bag.   Will steal that brillant engineering solution.   

Dennis

[Todd Stevens]

Well what’s the lowest device in the circuit? (Closest to the bilge.) Maybe start there? Oil pressure sender? But working through it systematically might be faster than random targets.

Todd

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[Dennis Boyd]

Thank you Todd,

I will attempt that approach.     If they are daisy chained, one fault could be the culprit 

Off to the engine manual.  There must be a diagram or two

Dennis

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From: 'Todd Stevens' via J/4X Owner's Group <j4x-owne...@googlegroups.com>
Sent: Friday, 12 June 2026 17:37:18
To: j4x-owne...@googlegroups.com <j4x-owne...@googlegroups.com>
Subject: Re: [J/4X-owners] Engine Control Panel J/42 out?

 

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