This 4010D

Jim

Its not that complicated a circuit. 12 volts comes from the ignition switch to the 12 volt input terminal on the gauge. A wire goes to the sender and the sender flange plus the gauge case are grounded to the other side of the 12 volt circuit.

Even with the wrong polarity it will still work. It might read off, but you can adjust that by bending the float arm on the sender. You can run it on the bench without the tractor if you have a source of 12 volts DC.

In one post you say you find 12.9 VAC? There's no handy source of AC on the tractor other than inside the generator or alternator. But many AC meters will indicate a voltage with DC applied.

I switched my gas 4020 from positive ground to negative ground when I installed the alternator. The gas gauge still indicates, once I fixed the sender.

With the sender out of the tank and with a wire from its flange to ground, moving the float arm MUST change the gauge reading as well as the voltage across the sender. If those don't change when you move the float arm, the sender is bad. If grounding the wire that goes from gauge to sender doesn't move the gauge, the gauge or wire is bad. That wire from the gauge to the sender is highly suspect. Try a new hunk of wire there. Be sure of the gauge and the sender grounds and of the sender function.

Gerald J.

IIRC, it operates on the (+) grounded 12-Volt half of the split 2-Volt system.

So, you should be seeing (-) 12 to 14 Volts, with respect to the chassis, as power to the gauge.

Once you have determined you have (-) voltage to the gauge, and the gauge is properly grounded, take then wire off the sender. The gauge should go to one extreme ("E" or "F"). Then, ground the wire to the chassis at the sender. The gauge should swing to the other extreme.

Often, over the years, the polarity of the connections got swapped at the LH and RH batteries, and the generator got polarized accordingly.

Here's a link to "gwece's" diagrams:

• 4010 wiring

Jim

AR46271 comes up unpriced. (And unavailable, it turns out.)

I called my favorite DEERE partsman, and he checked and determined RE54427 OR RE53644 ARE acceptable substitutes for AR26271.

Have you determined the polarity of the "feed" voltage to the gauge, with respect to the chassis?

Have you tried disconnecting, and alternately grounding the sender wire, and observing what the gauge does, as I mentioned before?

There are different gauges and sending units for 12v vs 24v from what I understand. Could you have a mismatched set?

Jim