Review on 🔊 APIELE 16mm Momentary Speaker Horn Switch: 12V, 1NO 1NC SPDT, Pre-Wiring Socket, Green/Silver Shell by Kaushik Sokolowski

As many have said, the schematic has nothing to do with reality. Instead of sending it back you can mess with the voltmeter but after all the complaints about the production there is still no quality control. In my case for the horn button the yellow goes to the battery and connects to the red which is the LED. Blue is the positive signal and black is the negative signal and battery. Green is not used. Another downside is the thread length, which is only 1/2 inch. My boat's console is 1/2", so I had to countersink a 1/4x1 1/4 in the back to install the nut. This unit is designed for 1/8" dash panels. I ended up with it satisfied, but the seller is doing something to improve the product.