Garmin Smartcraft connection question

[BellevueDA]

Hello,
Finally got the Garmin 942 connected to my engine. Love getting all the engine data on the Garmin screen..

I wanted to have the original Smartcraft and dash gauges also display, so I got the correct connector and connected the Smartcraft to the Junction Box and it still does not come on.?

Is there something I am missing to connect? Is there a way to display engine stats to Garmin and Smartcraft simultaneously?

Thanks everyone!

 

[bobeast]

At a minimum, you need a SC junction box with the appropriate cabling and terminators. I assume you used a gateway to get from SC to your Garmin. That gateway will go to one port of your J-box, and the SC gages/displays will plug into it as well.

- terminated cable from engine -> j-box
- gateway from j-box -> garmin
- cable from j-box to SC gages/displays
- terminator for the j-box (if not built into gages)

 

[rmlsll]

At a minimum, you need a SC junction box with the appropriate cabling and terminators. I assume you used a gateway to get from SC to your Garmin. That gateway will go to one port of your J-box, and the SC gages/displays will plug into it as well.

- terminated cable from engine -> j-box
- gateway from j-box -> garmin
- cable from j-box to SC gages/displays
- terminator for the j-box (if not built into gages)

If you have a extra junction box port left over, do you need a terminator or a weather cap on the extra port ?

 

[bobeast]

Well, you need a terminator on that end whether its plugged into the J-box, integrated into the gages, or built into the cable (all 3 are possible). As for weather caps, they are just that. If your j-box is mounted were it is certain to stay dry, not having a weather cap wouldn't affect the functionality. Either way you only need a total of 2 terminators, one for each end of the buss.

For a single engine setup, you will typically use a terminating cable (termination at the engine end, and then at the j-box the typical setup is to use a plugin terminator taking up one port of your j-box. If you run out of ports, you can go with a 6-banger or even daisy-chain another j-box.

 

[BellevueDA]

At a minimum, you need a SC junction box with the appropriate cabling and terminators. I assume you used a gateway to get from SC to your Garmin. That gateway will go to one port of your J-box, and the SC gages/displays will plug into it as well.

- terminated cable from engine -> j-box
- gateway from j-box -> garmin
- cable from j-box to SC gages/displays
- terminator for the j-box (if not built into gages)

 

[BellevueDA]

Thanks for your reply.

Engine —> SC Junction box —> Gateway —-> Garmin.

SC Junction Box ——> SC .

SC does not come on..

It should be possible to have both Garmin and SC on at same time right .?

 

[BellevueDA]

Everything you said except “terminator for the junction box”.. what do you mean?

a cap ?

 

[bobeast]

Yes. there is no reason you shouldn't be able to run both the SC gages and the gateway off the same junction box.
A terminator is not the same thing as a weather cap. It is a specifically designed part that is used to reduce reflections on the SC buss, although it does look a lot like a "cap"

https://www.mercruiserparts.com/859318t1-terminator

The terminator will always be Yellow. Weather caps are typically purple.

https://www.greatlakesskipper.com/m...MIqp290MPB6QIVGR6tBh3v4g9qEAQYAiABEgJGqvD_BwE

 

[BellevueDA]

Yes. there is no reason you shouldn't be able to run both the SC gages and the gateway off the same junction box.
A terminator is not the same thing as a weather cap. It is a specifically designed part that is used to reduce reflections on the SC buss, although it does look a lot like a "cap"

https://www.mercruiserparts.com/859318t1-terminator

The terminator will always be Yellow. Weather caps are typically purple.

https://www.greatlakesskipper.com/m...MIqp290MPB6QIVGR6tBh3v4g9qEAQYAiABEgJGqvD_BwE

 

[BellevueDA]

So if I just use a weather cap since mine is purple could that be the problem ?

what does a terminator cap do exactly?

thanks

 

[bobeast]

So if I just use a weather cap since mine is purple could that be the problem ?

what does a terminator cap do exactly?

thanks

This may or may not be your specific problem, but you have to start from a known correct configuration before you can troubleshoot any further.. You really do need a terminator at each end of the buss. The terminators contain resistors that prevent electrical noise from interfering with data on the bus. The weather cap is just a piece of plastic.

Here is a general document showing typical configurations;

https://www.drev.se/Upload/DocumentManager/mercruiser/smartwire.pdf

 

[BellevueDA]

Thanks so much for your help.

I just ordered the cap.

hopefully that works

thanks again

 

[Stray Current]

I have both a Northstar gateway and a NMEA2000 gateway plugged into my smartcraft junction box. I can tell you for sure the Northstar gateway doesn’t read unless under tension or compression. I cinched it with a zip tie

 

[BellevueDA]

I have both a Northstar gateway and a NMEA2000 gateway plugged into my smartcraft junction box. I can tell you for sure the Northstar gateway doesn’t read unless under tension or compression. I cinched it with a zip tieView attachment 85381View attachment 85382

Are you using a 4 port junction box?
If so did you have to use a terminator plug for the empty unused port for it to work?
I don’t quite understand what you mean but cinching it tight?

 

[Stray Current]

Are you using a 4 port junction box?
If so did you have to use a terminator plug for the empty unused port for it to work?
I don’t quite understand what you mean but cinching it tight?

Yes, 4 port box. No terminators/weather caps on the unused ports, there never were. When I bought the boat that had the one cable from the engine and the other cable from the smartcraft gauges plugged into two of the four ports.

I don't have any smartcraft gauges anymore. Just the one livorsi mercmonitor plugged in that functions as a digital multifunction gauge and nmea2k bridge, and the Northstar bridge.

The zip tie goes all the way around to of the plugs around the box. Basically it just keeps steady pressure inward on two of the plugs.

unfortunately the second bridge and ziptie was a late addition and don't have any pics. 3rd plug is in the bottom and zip tie goes around the bottom two

 

[BellevueDA]

Yes, 4 port box. No terminators/weather caps on the unused ports, there never were. When I bought the boat that had the one cable from the engine and the other cable from the smartcraft gauges plugged into two of the four ports.

I don't have any smartcraft gauges anymore. Just the one livorsi mercmonitor plugged in that functions as a digital multifunction gauge and nmea2k bridge, and the Northstar bridge.

The zip tie goes all the way around to of the plugs around the box. Basically it just keeps steady pressure inward on two of the plugs.

View attachment 85384unfortunately the second bridge and ziptie was a late addition and don't have any pics. 3rd plug is in the bottom and zip tie goes around the bottom two

I see the 4 way junction box that has the engine data line going into it and then the Gateway line on the other side.
I reckon the gateway line then goes to your Simrad.

Trying to get the arrangement.

Engine --> Junction box

Junction box --> Gateway ---> Simrad

Where did you get the line ----> to Northstar?

 

[BellevueDA]

i just read your the last sentence...where you said you added the other part later.

I guess my issue is:

With a 4 way J box, if only 2 ports are used, the other empty 2 can be left open , however if you have 3 ports used, do
we need a terminator cap for the last unused port (to complete the circuit) ?

 

[Stray Current]

I see the 4 way junction box that has the engine data line going into it and then the Gateway line on the other side.
I reckon the gateway line then goes to your Simrad.

Trying to get the arrangement.

Engine --> Junction box

Junction box --> Gateway ---> Simrad

Where did you get the line ----> to Northstar?

i just read your the last sentence...where you said you added the other part later.

I guess my issue is:

With a 4 way J box, if only 2 ports are used, the other empty 2 can be left open , however if you have 3 ports used, do
we need a terminator cap for the last unused port (to complete the circuit) ?

Correct this was added after the pic I posted. I do not have any terminators or caps on the unused plug. This particular piece did not function unless you pushed on the plug or pulled on it. If you just left it sitting it would not communicate. that's where the zip tie came in just to keep pressure on the plug.

apparently this thing hasn't been made in 10 years I was amazed to find it new in box