2005 290 Open Ignition Switch - Diesel

I have a 2005 290 Open that acted strangely today! When I turned on the main power circuit breaker, the warning horn came on while the ignition was off. My oil pressure went to 40 psi without the engine running. I started the engine and ran it a second to build oil pressure after an oil change and then could not shut it down by turning off the ignition switch. I had to turn off the main DC breaker for the engine (not the main battery switch).

I suspect the ignition switch is bad, but wanted to run this past the group. Any thoughts?

Sorry about that. 6LPA-STP Yanmars.

Working from 600 miles away with pictures and the wiring diagrams in the Yanmar OM manual, these are DPDT on-off-(on) toggle switches. I have ordered two 25A Carling switches and will change the port out when I get back to the boat.

If the switch is bad, corroded internally likely, it may have only allowed a small voltage through, appearing to the oil pressure gauge as a valid voltage from the sensor. xVDC = X psi.

Ok, I found the problem. Embarrassing as it is, the ignition switch in the tower was in the run position! Not sure why I had the indications on the gauges I did, but turning it off resolved the matter, right after I replaced the ignition switch at the helm!

I need to update this thread with the correct switch. The ignition switch is NOT a DPDT switch, it is a progressive OFF-ON-(ON) switch meaning it maintains the connection to the 12vdc source on the run side when moved up from the on position (center) to the start position (momentary on). It appears to be a DPDT switch with only two sets of pins, center (common) and one end. I found this at Mooreparts . com and paid about $21.00. It is a:

• K Four Item #13-221, Off / On / Momentary On For Ignition Start 20 Amps and Sealed Toggle Switch With Tab Terminals

http://www.k4direct.com/k-four-swit...gressive-12v-off-ign-on-ign-mon-on-20amp.html​

This 2002 (not a 2005) boat is equipped with a VDO instrument panel and a Luhrs console, not a Yanmar instrument panel.

Update - Carling switch to use for start/run switch - STM2EE-53 toggle switch. Drawing attached that includes explanation of how the progressive switch actually works.