Yanmar 4LHA C-panel dead

[timcub]

I hope this is the right forum for my question but if not please feel free to redirect me. Anyhow, I have a power cat with twin Yanmar 4LHA's. The starboard instrument panel is now dead. Cannot start or stop the engine. No tach/temp/oil pressure/lights/alarm. Must use remote switch to start and stop. This problem started out intermittently a few months ago. Initially the key switch would start the engine on an intermittent basis and the instruments all worked and you could stop the engine with the RED button. My Yanmar mechanic said try replacing the starter relay. I did and no improvement. Still intermittent. Next he said try replacing the key switch. I did and still had this intermittent start problem. Now more recently the entire instrument panel is dead. Nothing. The engine can be started remotely but the panel is still dead. Anyone have any thoughts where to look next?
Thanks in advance!

[skipperpete]

I’d advise taking a close at the main harness connection plugs, they get dripped on by salt water from time to time and cause problems. Here’s the wiring diagram from the most popular panel, hopefully it will help with troublshooting

[timcub]

OK so I started trouble shooting with the wiring diagram and started at the instrument panel. With the key OFF, I checked voltage on red/white wires on switch & I get 0 volts. I should have 12 V and confirmed with the port engine. Next I found the same wire connector in the engine room and check voltage there. Again, 0 volt. Then I checked the voltage at the starter relay (red/white wires) and again 0 volts. Checked the port engine and have 12 volts. Any idea where to look next?

[timcub]

Originally Posted by timcub

OK so I started trouble shooting with the wiring diagram and started at the instrument panel. With the key OFF, I checked voltage on red/white wires on switch & I get 0 volts. I should have 12 V and confirmed with the port engine. Next I found the same wire connector in the engine room and check voltage there. Again, 0 volt. Then I checked the voltage at the starter relay (red/white wires) and again 0 volts. Checked the port engine and have 12 volts. Any idea where to look next?

OK disregard most of the above. Brain fart. Battery was off. I do get 12 volts at the key switch with switch in OFF position but when I turn the switch ON, I get 0 Volts on the red & white wires whereas the port engine is still showing 12 volts. This is a new switch and it did work for about 2 weeks.

[skipperpete]

Here’s a clearer and more recent wiring diagram, I tried following the individual wires in my earlier post with no luck and found this in the front of my e. manual. I would be looking at the engine earth bolt, one of the wires might have corroded through and fallen off. There is also a chance that the second key switch has failed, possibly due to some sort of overload or short.

[timcub]

Found the problems.
The stop solenoid relay pins were all corroded and the red wire coming from key switch was completely corroded at a splice between alternator & starter.
Got a new relay and put a jumper wire on to test and now she starts and stops from the instrument panel.
The diagram definitely helped in trouble shooting.
Thanks again!

[skipperpete]

That is some ugly corrosion. Good work and thanks for the update.