Smartcraft on a pair of 2005 300X's

[Nick225EFI]

Afternoon !
I have a pair of 2005 300X's that I bought a set of Smartcraft gauges for, 2 x SC1000 System Tach's and an SC1000 System Speedo, the blue backed gauges, they are 2015 year gauges, so the calibration is a little different to the older gauges.
The original set up is with two blue Can Harnesses with terminating resistors at each engine.
Initially the set up was with a single 6 way junction box, all worked except one ignition switch powered the whole system, including both analog voltmeters, switching the 2nd ignition on produced no beep from the guardian horn. See Pic 1.
I bought a Smartcraft manual from 2016, followed the instructions & architecture for dual engines, two 4 way junction boxes, the multiwake link wire P/N 892323T01, connected to the SC1000 Speedo, and the CAN P link Wire P/N 891957K01, connecting both 4 way junction boxes.
This follows the exact diagram set up in the Smartcraft manual, see attached PDF File. The system functions exactly as expected, except one thing, the left SC1000 tachometer does not power up.
I have a DDT with 1.31 cartridge, the engine locations have both been assigned repeatedly.
I have swapped all components and all is functional, however, the left tachometer will not power up in the correct configuration.
Left ignition on powers the speedo, but not the tachometer, the right ignition on powers the right tachometer and speedo.
I understand that Smartcraft has a bunch of configurations, but I thought I would throw it out there to see if anyone had an idea on this. Is the Can P link wire the correct one ? Each engine has a Can P power supply, these 3 pin connectors are both closed on the engine.
Thanks for any thoughts you may have,
Nick

[mrpenguin]

Seperate the systems into two completely separate CAN entities. Port and starboard. Eliminate the speedo until you figure out the issue or just leave it on the starboard but not connected to the port system. Also try swapping the tachs and go into CAL2 to swap the engines.

[25two.stroke]

Did both tachs work correctly for their motors the way it was first set up?

[Nick225EFI]

Thank you both for the replies:
The Smartcraft system worked well on the initial set up, it was just all powered from a single ignition. Which wasn't good.
I have swapped around all the parts to prove harnesses & gauges, all work fine. I didn't think of full segregation to prove the engine itself, but I will do that when I'm next at the boat. I will also see what I can measure with a multimeter from the smartcraft book. As I recall the 10 pin connector is integral to the main engine harness, but I can measure the 3 pin power link harness just back from the 10 pin connector.
Thanks again for the replies, I will read the book again and use the idea's you have suggested.
Cheers,
Nick

[25two.stroke]

It all being powered off one key is not uncommon. The starboard most engine on mercury rigging is the main/master/control engine whatever you wanna call it. That should be the key that controls it. However, you can isolate the two engines and then run the speedo off the stbd or theres another option.
Not sure what wire you are using for the CAN link harness but you can use a 2 wire if you aren't already. You don't need a 10 pin between the busses. If you have a modern wiring harness with smartcraft built in then the blue terminators on each harness can be removed and a can link 2 wire can be connected between the 2 key harnesses. This wire does not carry power, just the data when both sides are woken up.

[Nick225EFI]

Thanks for the addition 25Two.Stroke,
It will be a few weeks before I can get back to the boat.
The multiwake harness for the speedo is P/N 84-892323T01, the Can P link Harness is P/N 84-891957K02.
I will follow your suggestions, what is the two pin harness you are talking of ? Where would this be connected, please ?
Many thanks, Nick

[Nick225EFI]

Firstly thanks for the advice, I finished separating the systems down, all harnesses were proved to be good, so the issue had to be with the engine.
I went back to the smartcraft book which spoke of blowing fuses if wired through a single junction box at the helm (the initial set up) .... and finally to the 300X wiring diagram at the back of the manual. Traced the wiring back and there is a Smartcraft fuse in the fuse box, blue 15 amp. This engine had a Tan 5 amp, which had blown, as they are new to me, maybe blown before I had the engine.
Fuse replaced with the correct, blue 15A job and all works as it should now, the system is set up as a segregated system, with the multi-wake (Harness P/N 84-892323T01) & link (the Can P link harness is P/N 84-891957K02, blue & white wires only) harnesses in place between the junction boxes. As per the Smartcraft diagram in the original post.
Thanks for the help.
Best wishes,
Nick