Yanmar Engine Panel Warning Light Diagnostics

When I first bought my boat, the cockpit “dashboard” engine panel was something of a mystery. There were six little warning light windows, and none of the lights ever came on.

Crusty with California Ashes

Mine is a “Type B” engine panel, and I did some internet reading and purchased a Chilton owner’s guide for my 3GM30F engine. I thought I would try to make some of the lights come on.

The backside of this panel is in my starboard cockpit locker. The wires that protrude from the back are protected by a cover inside the locker. I removed the cover, and this is what I found:

Only four of the six windows have bulbs behind them, so already I had solved (explained) 1/3 of my non-functional lights. I started wiggling some wires around and then turned on the ignition. Lo and behold, two of the lights came on (there must have been a loose connection I ‘fixed’).

Low oil pressure light, and low charge light came on. At least I know the bulbs illuminate.

I tested the other two bulbs with these functioning sockets and sure enough all four of my bulbs were good. One slides the rubber housing out of the round hole and removes the bulb from the rubber.

The third light is the water temperature light – as in, is the engine overheating.

I read a couple of different explanations on-line. One said that all of the lights should come on when the ignition is on, but not cranking. A second said that the water temperature light will not illuminate because it will only work when the water has actually over-heated.

I had also read that the black toggle switch to the left of the ignition key is for testing the bulbs. So, with the ignition on, and a little more wire jiggling, I made the third light come on! Even more progress.

And the fourth bulb? After more reading, I learned it is for the ‘Sail Drive Gasket’ warning. I found this curious, because I don’t have a sail drive. A sail drive looks like this:

GM/YM Series Saildrive 9-29MHP | Sailing Engines | Marine Engines

The sail drive relies on two gaskets between the hull of the boat and the drive portion that extends out of the boat. If water leaks in that area, it’s a big deal because the boat will sink. Hence, Yanmar made a warning light, in case the outer gasket failed. Good thinking.

My engine is connected directly to a propeller shaft. It doesn’t have a sail drive.

“Wait, so you have a wired sail drive indicator light but no sail drive? Does that mean there are some loose wires dangling unconnected somewhere because Yanmar used the same wiring harness for both shaft and sail drives?”

Yes, that is what it means. A nice connector, hanging out in my engine bay, doing nothing.

So, fewer mysteries as to my engine panel. I have six warning light slots, two are empty, one is fake wired, and the three that are supposed to work:

Oil pressure warning

Low charge warning

Water temp warning

All have functional bulbs and can turn on. I suppose I need another round to test whether the signal senders are working properly.

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