VesselView & starboard voltmeter show incorrect voltage

[Seapig]

I have a 2012 SeaRay 310 Sundancer HID#SERT4123A212 that has twin Mercruiser Mag 350s with Bravo drives, Axius system, Vessel View & DTS. I'm bothered by a .5 to 1 V lower-than-actual voltage indication on the starboard voltmeter and on the Vessel View starboard indicator. I have confirmed with a Fluke DVOM that the starboard battery voltages at KOEO and running are normal (12.6/14) The starboard system powers the “house” and the voltages at the house fuse panel are normal. I've poked around on the engine and found normal voltages at the main breaker, alternator battery lug, and on all 8 engine fuses but the instrumentation shows ½ to 1 V low at most times. It seems after an hour or so of run time, the error may become minimal.

I'm assuming that the gauges are networked on a CAN network and the voltages are not raw inputs but rather data sent by a module on the boat's network.

I have a Diacom scan tool and the displayed (battery voltage) data agrees with my instruments so I'm assuming one module is reporting incorrect voltage. What I'd like to know is which module derives battery voltage and on what pin/circuit so I can measure it at that point. Daicom shows starboard “system voltage” accurately and it agrees with what I measure and what we'd expect but the starboard “battery voltage” is wrongish.





ESN#2A014627

 

[Espos4]

When checking at the battery, there are a few different ways to test voltage.

Putting the DVOM probes on the heavy cable terminal ends is different than putting the probes on the actual battery terminals.

Good clean connections will show the same results. But if you get different results from these 2 methods, that would indicate loose or dirty connections.

Also, I believe that the ecm harness uses one of the smaller ground wires at the battery, so be sure to check and clean all of the battery cables.

A poor ground connection can easily show lower than the actual battery voltage.