The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - What does the fuel gauge do when truck is off?

**pjmoreland** · 10-03-2022, 12:14 AM

The resistor is connected to 12V on one end, and the other end is connected to the tank sender. The tank sender is connected to ground. The variable resistance of the sender that's connected to the fixed resistor together make up what's called a voltage divider. The voltage of the junction of these two resistors changes depending on the position of the sender.

There are two sets of windings inside the gauge. They are both connected to the same voltage divider junction at one end. The other end of one winding is connected to 12V and the other winding to ground. This causes the windings to swap in terms of dominance of one over the other depending on whether the junction voltage is high or low. One winding pushes the gauge toward FULL, and the other toward EMPTY.

If the resistor fails open, then the balancing act of the voltage divider system is messed up.

The temperature gauge works the same way.

10-03-2022, 12:14 AM	#11
pjmoreland Senior Member Join Date: Jan 2005 Location: CA Posts: 6,241	Re: What does the fuel gauge do when truck is off? The resistor is connected to 12V on one end, and the other end is connected to the tank sender. The tank sender is connected to ground. The variable resistance of the sender that's connected to the fixed resistor together make up what's called a voltage divider. The voltage of the junction of these two resistors changes depending on the position of the sender. There are two sets of windings inside the gauge. They are both connected to the same voltage divider junction at one end. The other end of one winding is connected to 12V and the other winding to ground. This causes the windings to swap in terms of dominance of one over the other depending on whether the junction voltage is high or low. One winding pushes the gauge toward FULL, and the other toward EMPTY. If the resistor fails open, then the balancing act of the voltage divider system is messed up. The temperature gauge works the same way. Attached Images Last edited by pjmoreland; 10-03-2022 at 12:27 AM.