Setting fuel pressure on Garmin G3X

Uri, the ECU 1 AND 2 voltages are measured by the ECU itself and transmitted digitally by the CAN bus. You do not have access to measure them yourself.

The amperage shunt should be somewhere in the aircraft and it’s connected to your EFIS.

Uri hadar wrote:

Hi Jeff,

If possible, it will be of great help if you can send me a snapshot of:

1. The Engine and Airframe Configuration Page 

2. If you can go inside the Volts 1+2 and Shunt 1+2 just to see the Gauge display range and marking

attaching my cfg snapshot

Thx!!

Uri, 

These photos show how my aircraft was set by the manufacturer.  However, I don’t fully agree with them.  For instance, I think the yellow zone for the battery low volts should start closer to 12.7 volts, which I believe is just about the standing voltage of a fully charged 12v battery.  Remember, these are for my particular aircraft and are not necessarily correct for yours.   

Hi Jeff,

Thank you very much! I truly appreciate your help

I agree the configuration is airplane specific, there are things that are not clear to me in the configurations

G3X installation manual says:

Mine is configured a bit differently, see photo.  I assume bus 1 volts is looking at the airframe bus, and the FADEC ECU bus B is looking at the engine specific bus.  I know that if one alternator fails the engine bus gets priority, at which time I would expect the airframe bus (1) would begin to discharge.  I’ll be interested in what you find out with Garmin.  

Hi Jeff,

This is the question I sent to Garmin and the answer I received 

Mail sent:

Hi, 

I have few questions on how to correctly configure G3X EIS electrical view with Rotax 912 iS Sport and a GEA 24 Voltage: 

According to the installation manual for the GEA 24 and Rotax (912iS/915iS – both Lane A and Lane B) I set in the engine/airframe Input Configuration as follow: 

Volts1 - Rotax FADEC ECU Bus A Volts 

Volts2 - Rotax FADEC ECU Bus B Volts

1. Is this the correct setting?
2. Under this setting, is there a way to also display the Battery voltage?
3. I also have TCW IBBS-12V-6AH backup battery, according to the installation manual I can display its voltage by setting "VOLTS 2 INPUT TO DISPLAY ESSENTIAL BUS VOLTAGE”. 

     Is there a way to display the backup battery voltage if Volts2 is displaying ECU Bus B?

4. What is the difference between setting Volts1/2 to “Bus 1/2” or “EIS Power Input 1/2”?

 Current:

 In my installation, Shunt1 is connected to Pin 36+37 and to the Battery,

 what should be selected in the Shunt1 input in the configuration menu?

1. "Bus 1 Amps”
2. "Main Bus Amps”
3. “Alternator Amps” (This option does not appear in the installation manual)
4. “Battery Amps” (This option does not appear in the installation manual)

Is there a difference between them or is the only difference is the text labels used to display current gauges in EIS display? 

Response from Garmin support:

Yes, you are correct regarding the Volts1 and 2 configuration.

I think it would be best to use one of the General inputs for the battery voltage:

 Regarding the Volts1/2 to “Bus 1/2” vs. “EIS Power Input 1/2" difference is well described in the installation manual:

 Regarding the current: the configuration will not change how the information is processed by the system. Only the label on the screen will change. Probably Main BUS would be the one I would go for. 

Kind regards

As for the voltage,

Setting the Volts 1&2 to Rotax FADEC ECU Bus A/B Volts is also what my mechanic recommended me to do in order to track voltage supply.

(Initially my set up was Volts1 = Rotax FADEC ECU Bus A Volts, Volts2 = Bus2 Volts")

I did not understand from the installation manual what is "EIS Power Input". Perhaps it is same as Rotax ECU for non Rotax fuel injected engines?

As for the current, 

In my setup Shunt1 is set to Main Bus Amps, and the shunt is connected to the battery. It shows well the current drawn or charged into the battery