I have a 1985 Sumitomo excavator with a 4JB1 Isuzu engine. Recently the temperature gauge stopped working (buzzer sounds, light on the dash, gauge doesn’t move). I have ordered the sensor for this. It has a single wire going to the sensor. Should this wire be power or a ground? I tested it and it seems to be a ground wire? Is there any way to test this wire to make sure it’s not a problem with the wire or gauge? Thanks
Typically sensors have a single wire coming from the gauge and they vary the resistance to ground based on temperature or pressure. So the wire is the ground for the gauge, and the sensor controls the gauge by the varying resistance to ground. The way to test is to touch the wire direct to the ground with a small clamp and see if the gauge goes to the full range, then disconnect it and see if it returns to zero movement. If it does both those things, then you can assume the sensor will fix it. That's assuming the sensor is wired directly to the gauge, newer machines will have everything run to a control board/computer, but I think yours is old enough to be simple.
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