S4 fuel gauge

[JohnMorin]

Hi

In the process of replacing the dashboard I'm checking that everything works before I screw it in to position.

The fuel gauge is not working although it was before I took the old dash out. I labeled everything before is disconnected everything but now I wonder whether I got something wrong. There are two terminals on the back of the fuel gauge, can someone please tell me which takes power and which goes to the sender.

Thanks

John

[elanner]

I don't remember the workings of the fuel gauge but isn't it a bimetallic strip that bends (moving the needle) as the current increases/decreases due to the resistance of the petrol tank sender changing as the float goes up and down? If so it's current driven so it shouldn't matter which way around the wires are connected, right?

You can easily check if the gauge works by wiring it directly across the battery for a few seconds (not for too long, to avoid any risk of of over heating the bimetallic strip).

You can check the sender by measuring the resistance between the sender wire and ground. It'll vary, depending on how full the tank is, but as long as it's not open circuit it won't be the cause of your problem.

The gauge is powered by the 10V regulator that hangs off the back of the tacho. You can bypass it and temporarily run the gauge directly off 12v. It'll simply read high.

Nick

[JohnMorin]

Thanks Nick

Problem sorted. Despite carefully labelling everything (I thought) I managed to mix up the washer feed and the wire to the fuel tank sender. Swapped them over and they both worked.

John