Suzuki 300 error on port and starboard 7-1, 3-4, 2-1

[Oceanslayer11]

Good morning, any help would be greatly appreciated. 2018 twin 300 fly by wire. Dealer just replaced ecu, motor wiring harness, sub wiring harness, throttles, engine interface cables(3.5.7), push button start, and key switch due to insurance. I am now getting following errors: check throttle system, 7-1, 3-4, and 2-1 on both motors. Batteries and grounds are good. Dealer is about an hour away so I’m trying to do this myself without having to tow it back to dealer. I have removed everything from nmea network with exception of motors and c10 to ensure no interference. Thank you!

[Murray]

Often multiple codes can be caused by low/week battery/batteries. I realize you say the batteries are good but it might be worth getting them load tested.

[Oceanslayer11]

They were load tested already.

[Moonlighter]

Multiple false codes are almost always associated with voltage issues - which in turn are due to the batteries themselves, or their wiring, or the engine harness.

All it takes is a chafed wire or bad connection in the harness, corrosion in a battery lead, a bad battery switch, or a poor connection in the ecu connection/battery sub wire (the white wire). Anything along those lines. Unused harness wires that are not taped up and touch each other also cause issues.

Although a new harness was installed, its worth checking all those connections are correct and that no pins in plugs are damaged or wires are loose or broken. Test all the battery cables for resistance, because internal corrosion can compromise them.

In rare cases I have heard about harness plugs wired wrong. Rare, but human error can and does happen.

What was the event that lead to the insurance claim and replacement of all those parts? Was there a fire, or was the boat submerged or something?? Must have been a major event to warrant all that stuff being replaced!

Did the dealer do the initialisation procedure again CORRECTLY after replacing the ecu’s and harnesses etc? And surely, after all that replacement work was done, they must have started the engines up and verified that all systems were operating correctly? Which would have revealed these false codes - or did that happen later?

[seameafterclass]

Having exact same problem on my 2015 250. I think it’s the harness from the engine to the helm, but there are none to be found anywhere and it’s back ordered. I found stiff wiring in the bilge and I’m thinking that is the main issue… keep us informed of solutions. I have replaced interface cable, batteries load tested ok, new battery cables, new engine wiring harness, new ECU, and still have the same issue. White wire is now being replaced, so we will see if that helps.