2003 CH613 Fuel Gauge-how does it work electrically?

[Dakota]

Bought a used truck a while back and the fuel gauge didn't work so the dealer gave me a new sending unit.  The new sender only has one wire going to the connector and one grounded to the mounting plate of the sender.  The electrical connector from the truck has two or three wires to it and the sender has a connector that will fit it but, as said above, only has one wire from the sender to the connector.  I can't get the gauge to work so I'm wondering how the sender works, electrically.  If I ground that one wire directly, would that make the gauge in the cab register something?  That seems to be the only possibility.  Or did the dealer just give me the wrong sender unit?

TIA,

Steve

[Mackpro]

Most all the CH/CX style trucks around that time had 3 wires on the chassis harness but usually only 2 wires on the fuel sending unit . The third wire was for a optional style of sending unit that was rarely used. If your dash is the flat panel dash with the old style odometer with the rolling number then the wires from the fuel tank sending unit go pretty much straight to the back of the fuel guage . If you put the two wires together on the sending unit the guage should go to full if the wires are not cut or guage is not bad .  If you have the newer rounded dash that started with the CX and then used in the CH trucks  and has the digital odometer in the middle upper part of the dash cluster, the fuel sending wires goes to VECU ( vechicle ECM) located in the kick panel in front of the passenger seat. Putting the two wires on the fuel sending unit on this style does nothing to the guage . You will get fault codes with this style if the wiring or sending unit is bad .   

[Dakota]

My sending unit has two wires but one of them goes directly to the sender mounting plate--as a ground, I am guessing and only one wire goes on to the harness to the truck, which has a connector for three wires-but there is only one, from the sender, at that point.