Thats weird they must be extremely sensitive. I checked mine again while having it plugged in and it jst goes to almost full on gauge when float is at stop point on one side and it goes to just above the E for empty when at stop point on other side. But no light comes on. I also notice now my instrument cluster won’t light up anymore. It used to but it half lit up recently and now not at all. I reckon it’s a separate issue from the fuel light as it all worked for a long time before while I had no reserve light working.That's a normal Toyota fault I'm afraid, mine worked perfectly then changed tank(same sender and pump)and then it started messing around, clean what crap you can of the terminals so it has a good earth, if you do get a 2nd hand one you can test it buy plugging it in under the seat and slowly moving the level arm by hand
Does anyone know if I can get a replacement fuel level sender on its own and if so where? Also are Glanza/or other Toyota fuel pumps and level senders the same if needed?