GRT Avionics

GRT Support,
I'm using a couple of Rochester Resistive Float-Type Fuel Level Sender (30-240 ohm). In wiring this can you advise on my two questions below?

1) Can I use the EIS Ground from connector A, Pin 1 as a ground for the Rochester gauge ground? I'm running a twisted pair wire from the gauge down to the EIS and it would be quite easy to Raychem solder sleeve a pigtail ground out of EIS Pin 1 to provide grounds for the two wing tank fuel gauge grounds.

2) When wiring the 470ohm 1/4-1/2 Watt resistor in line with the 4.8V Excitation (Connector 25, Pin 25), I assume I need a resistor for each tank gauge sending unit I wire? Or can I just put the single resistor on the Output from Pin 25, and then split a single wire to each resistive sending unit (LEFT and RIGHT tank gauges)?

Thanks for your help.
Howard

#2. You need 2 resistors, one for each tank. Otherwise left and right will read the same.

As a follow up for others who may have this same question.

GRT Support did confirm I can use the EIS ground (Connector A, Pin # 1) as a ground as well for the Rochester Resistive Fuel sending units. It's actually better to use the EIS ground to minimize any voltage differential when the measurement is done by the EIS. I plan to use Raychem solder sleeves with pigtails out of Pin #1 to the left and right fuel tank Rochester gauges ground wires.

Howard

FYI...The resistor limits current flow through sender potentiometer, otherwise it would burn up inside your fuel tank. I put one on each wire per diagram.