|
Kevin, for one thing, a fuel gauge MUST be matched with the correct ohms resistance value (typical maybe 0 to 35 ohms range approximate) tank sendign unit for it to read correctly. If your new gauge isnt the same as the old i.e. if it were designed for a different resistance tank sender (variable resistor depending on float level), it will not be accurate. If the gauge you purchased is original equipment Deere for your tractor, it ought to match up with the sender (assuming sender is good) and work. I have seen some gauges having an extra ground terminal which is just the ground return path for an internal light, not sure what yours has. The working gauge terminals causing needle deflection are the IGN (voltage when Ignition switch is ON) and SENDER (ground return path via the tanks variable resistor). Second, regardign polarity: If its a bi metal type in which current flow (regardless of direction) produces heat and deflects a metal strip, the polarity wouldnt matter regardign the direction of needle deflection. HOWEVER, if its a galvo type, whereby current flow produces a N/S magnetic field (dependant upon currents direction) the polarity would have to be correct. The gauge works cuz when the ignitions ON voltage is applied to one gauge terminal while the other terminal leads to the tanks float level operated variable resistor sending unit, and then to frame ground for the return current path. If you have voltage to the gauge, you test its basic operation by connecting the TO SENDER terminal to dead ground and then totally open/disconnected, and it should deflect approximately from Full to Empty depending on its design. Often, if you cant buy the exact gauge to match the sender you have, you have to buy BOTH a new gauge and sender which are designed to work together havign the correct resistance values. You might check with Deere to see if its the correct gauge for YOUR TRACTOR (Including Polarity), if not and you cant buy the correct one, you may have to buy BOTH an after market generic Gauge and matched Sender. Good Luck n God Bless John T jmn50@msn.com
|
