Twin 525efi's.Using 1 403 screen.
I cannot get it to display both motors.I only get 1.When wired up as a single it shows as the centre motor.
Have checked and double checked settings and connections.
Is there something i have to disconnect.I have also not entered into the screen which motor is port and starboard.
Any help appreciated.

What is a 403? Older smartcraft or vessel view? On the new Simrads/ vessel views there should be a “setup wizard” under the mercury setup tabs that will walk you through engines, fuel tanks etc. Do you have a manual?

It's the latest small screen and I used the setup wizard.Still can only get 1 motor to show.
Connected individually they work fine.

Wonder if your wired correctly
Is there a junction box for each motor?

Yes 2 junction boxes.
There was nothing i saw in the setup to tell the screen which was port and starboard??
I read somewhere that something needed disconnecting on 1 motor?

Motors are identified in the setup
Do you have the CAN P harness (g)?

On my 2 engine set-up I plugged into the 1 J-Box and both engines displayed. Its hard to tell by the photo if the boxes are linked in some way. I did have an older style Raceview that was replaced, probably why mine was plug and play. I bet it has something to do with you running 2 J-boxes, system not able to read both at the same time because both are not "on line" at the same time. .

1 J-Box in lower right corner

Yours is a smartcraft to NEMA install, which you should also have a SC gateway somewhere connecting at (a)

Looks like AllDodge has the answer with the CanP Link Harness. Never tried this but why can't multiple engines just plug into 1 J Box?

When I looked into doing this one of the steps was to have a dealer program the engines for port and starboard. They all come from the factory with the same setting and smartcraft can't connect multiple engines without being properly set first.