Engine data "crossing the streams"
 

I Have a pair of 525 efi's, a single j-box, vessel view link, and a 9" and 12" MFD and my starboard engine when running is displaying the info on the port and starboard MFD data field it does this with the port engine in any status(off/on/running). and when the starboard engine is off the port engine running will not display any info onto the MFD's, has anybody ran into this? bad junction block? bad vessel view link? bad engine ecu?

Where is your NMEA2000 backbone getting its 12V power from? If it's getting power from the Stbd engine then no power = no worky.

hardwired, so as long as the battery switches are “on” the network is powered.

Not sure where the link gets power from…. It plugs into the nmea network and the smart craft j-block…. Power from one of the 2….

this just happened, something failed, has been working for 2-3 years since the hardware upgrade…

Check fuses on the motors?

I forget, did you say you tried reprogramming or resetting up the Simrads? Do you have a junction block for each motor or one of the cables that takes the two blue cables from the motors and splices them into 1 then into the j block?

fuses good, 50 amp breaker next to fuses good(or not popped)

Simrads and vv Link had software updates, so I took care of that this afternoon did not fix anything.

I replaced j block this afternoon, did not fix problem. I have 1 j block at the helm with 1 blue cable coming forward so must have that diode harness in the boat someplace

other random things that I discovered/did not think of to put in here when I trim the right drive both indicators move on the displays when I trim the left engine it does move but it does not change anything on the displays. When I shift the right engine into gear on the display only the right engine shows in gear when I shift the left engine the left gauge indicates in gear. When I pull up the engine hours and RPM bands I know for a fact that they are not identical, so I am assuming both engines ours and rpm bands are pulling off of the right engine because they show to be identical on the display. so it is really odd that somethings are showing left and right engine separately and somethings are using right engine only data

I wonder if you could have a bad vessel view link module. The corrupted data would seem to point to there being a problem where the data from the 2 engines is joined together before being presented to the NMEA network.

I'd probably try switching the blue data cables between the 2 motors and see if the problem reverses itself.

Thought
 

Just a shot in the dark, but you might want to check to see if the engine assignments for port/starboard might have defaulted back to factory settings. I know when setting up Smartcraft on twin engines you have to assign side designations in the ECU or they report as the same as default. Why the engine assignments would change randomly when it was working before, I don't know.

really close here!

got mercury tech support on the phone to see what direction to go (bad link? bad pcm? etc) he had me put the old vessel view race view back into play, and that read the engines like it should!... put the link back into play and dug into the settings and some how the port engine got set to read the starboard engine for a data source! how that changed its self who knows!! but at least it was a rather simple and free fix