Well it has always been tricky to get circuits to work, but the information can be difficult to figure out and with kits like the Sunfounder you are go to find pin-outs are not correct. After a few hours of study, I figured out how to make the KY003 or 03 KEYES Arduino Hall Magnetic Sensor Module work. The trick was getting the small LED to light up when you put a magnet near to the transistor that kind of hangs over the edge of the board. When I got that to work, the signal line will now work.
So the pin outs are the following for my device, you will need to figure out the circuit on your own since it appears that the output leads vary quite a bit. This is likely due to the process that is used to fill the Sunfounder kit: Check what is in the remainders from a run of fabrication. This is not a lack of quality it is just the way to get these sensors into your hands to experiment with. This has been a long practice in hobby and even entrepreneurial efforts in electronics, textiles and so forth. Get used to it.
Ok here are the pin-outs, when you get everything hooked up, to test the connections, use household magnet, for instance on the back of most kitchen timers there is a magnet, which is what I used. The LED will light up when you get the magnet very close to the Hall Effect Transistor and Circuit. In some cases you will have the circuit connected correctly the magnet might not be strong enough. I had to use my handy multimeter to get this information, I was assisted by the tech sheet at:
Note that this appears to be a transistor, in reality there is a few logic circuits in the Hall Effect Transistor and circuit. It does create a clean output that is easy to use. In a later blog I will show how to use your Arduino to implement a simple Arduino program that will use this module.