No Temp Idiot Light After Lightning Strike (Yanmar 3JH2E, B-Type Panel)

[Jim-n-Bev]

Thanks to the forum over the years for wonderful advice and direction on many issues! I think this is my first post requesting assistance (as I can usually find my answers on existing threads). Here goes:

Boat struck by lightning and fried almost all electronics. Those items getting replaced, but my engine control panel is confounding me. I have a 1993 Yanmar 3JH2E with the B-Type Control panel. Before Lightning, turn the key "on", would sound alarm and light up charge, oil & temp idiot lights. As soon as engine started, buzzer would silent and lights would go off. After lightning, no buzzer and only charge light would display. Replaced oil and temp switches at engine and no change.

At that point, I googled to find more troubleshooting advise and found touching the temp switch terminal wire from harness/panel to the base of temp switch DID in fact set the alarm and idiot light - which indicates a bad temp switch. At that point, since it has a brand new OEM Yanmar temp switch, I figured I was in over my head and engaged a diesel mechanic, who replaced the B-Type panel and wiring harness. No change?! The new wiring and panel are clean and beautiful, but only the charge light comes on and no buzzer at key on before start. Mechanic declared temp and oil switch defective and chastised me for ordering Yanmar products "online" ordered new switches from his supplier.

New set of OEM Yanmar Oil & Temp switches arrived yesterday and I installed myself. NOW, I get the buzzer, Charge & Oil lights at key on, but still no temp light!? Temp terminal wire to base of switch will still set off alarm & temp light, but not when screwed into the working end of the switch. UGH!

Appreciate confirmation of my troubleshooting technique as well as any suggestions or recommendation on anything else to try.

Regards, Jim

[barnab]

Are you sure the temp light went on before starting? In my understanding:
The charge light is a "no charge" light, so engine not started = not charging = light on
The oil light is a "low oil pressure" light, so engine not started = oil pressure is low
The temp light is a "temp too high", engine not started = engine cold = no light


I have a Volvo in my current boat an no lights at all so can't verify here...I assume if you stick the temp switch in a pot with boiling water you will have the light and buzzer and not having the light before startup is normal.

[apoc]

I would think about replacing the panel.



I have a b type panel for my 3ym20. All lights come on with audible alarm when switched on, which is a feature to show they are functioning. I had a problem with an old panel where oil pressure light and temp high light would not turn on. Replaced the panel with the more modern version and everything worked.

[cram]

The temp light does not come on unless the engine overheats or you push the temp light test button. (Check switch)

[JoeRobertJr]

Originally Posted by apoc

I would think about replacing the panel.

From the OP:

Originally Posted by Jim-n-Bev

...At that point, since it has a brand new OEM Yanmar temp switch, I figured I was in over my head and engaged a diesel mechanic, who replaced the B-Type panel and wiring harness. No change?! The new wiring and panel are clean and beautiful, ...

If the system is designed to light up the temp light before starting, as a way to verify the lamp is still OK, then there is a path to ground separate from the temp switch itself. If you can get your hands on the panel schematic, you may be able to find that path.

As Barnab suggested, you could pull the temp switch and measure the resistance cold and measure again after putting it in boiling water for a while. You should see the resistance drop. That could eliminate the temp sender as the source of your problem.

[JoeRobertJr]

The following link has a schematic.

https://www.cruisersforum.com/forums...tml#post915981

The second path to ground that I mentioned is in the "Illumination Switch". So that switch might not be working as intended. You could start by checking the connections to that switch.

[JoeRobertJr]

I highlighted the switch in question.

[Jim-n-Bev]

Thanks all!

OK, barnab gets 3 gold stars! As sure I as was that the temp light came on at key-on, I went back to the service manual to confirm, but that manual did NOT specify temp alarm/light at key on. It did indicate light/alarm for the oil switch (which does work). So I farther went to the original Yanmar owners manual (PO very good at keeping documentation) - and there in the OM chapter 6-7 (checking pilot lights) it clearly states oil & charge lights on, temp light OFF. So much for my memory?!?!

apoc, I did sneak into one sentence of my manifesto that the mechanic did replace the wiring harness and control panel, but easy to miss in all the other ramblings - thanks for your feedback (essentially you were right, I did need a new control panel)

cram, my old panel DID have a "test" switch, but your suggestion to try that helped me realize the new panel does NOT have a "test" switch - oh well...

barnam & JoeRobertJr, I did take the temp switch and test in pan brought to a boil and confirmed the switch was good as I did get continuity on a volt meter when it was hot out of the water AND then when it cooled off for 10 seconds, continuity was gone - so thanks much for the troubleshooting technique to confirm switch was good and building the assessment that this engine and control panel are, in fact, working as designed...

It is a VERY good day - Thanks one and all!!!!