Another comms error

[markrona]

I have a 2012 Yamaha SX210, 280 hours with the check engine alarm on Port engine only. Diagnostics are fine, runs great, engines checked out fine, mechanic ran codes and is only finding one ‘unknown’ code, he has reset it and it comes right back. He checked all key wires and didn’t see anything odd. We did see the N2k and speed comm error when resetting using the key cycle method to reset the check engine light.
I replaced battery, terminals looked good, I did recently replace radio head unit but had it for about 20 hours last season and no issues. The alarm did start right after dewinterization - I just figured it was low voltage so I replaced battery. In other posts about this topic I see that the transducer has been a problem. While I am getting speed (mechanical on this model) and water temp, I forgot to check the depth gauge. So my questions - is only the port engine a clue? where is the transducer? If it was a transducer would the alarm show on both engines? What could have come loose from the radio that may not be obvious behind the radio? I have a cutoff switch for the battery, it’s clean but could this be an issue? Any other ideas would be appreciated, the mechanic spent about 3 hours and could not find it. I have been bragging about how efficient and easy this boat has been for tool long and it caught up with me. Thanks in advance - Mark

 

[tdonoughue]

Hmmm... This is a good one. Namely: I think you have done everything I would have done so far.

The mechanic: not a Yamaha mechanic? Do you know the actual code? I don't think these engines will throw an 'unknown', they usually throw a code (now, the meaning of the code may be unknown...).

I would not think head unit. You ran 20 hours with no issue. Even if you knocked something or something, it would have shown up right away.

Dewinterization... what all did you do for dewinterization?

The transducer (if it is like my AR240) should be starboard of midline, toward the aft. Should be able to see it from the bottom pretty well. Big black round disk. That will help you locate the inboard side of it. Again, if it is like mine, the transducer is plugged into the bus (not a specific tach), and then each tach is also plugged into the bus. Should have wires coming out of it that you can trace to a connector. There have been reports of problems at connectors causing weird problems (corrosion in the connector), so I would check that first. Also: on mine, the port tach is the master. So that is the one where alarms appear and where I silence them. No significance to it being that one vs the starboard...

 

[markrona]

Thanks for this, I did not know the port is the master. The mechanic is not Yamaha specific so now you got me thinking I better get the YDS. I thought unknown was odd. Will report back. Thanks