I have several of these 12v and 24v relays from Amazon.
They all act the same. I have 12v going to COM1. I have the 5v from the arduino going to D+ and the arduino ground going to D- and my output pin to IN1.
When I write HIGH output to IN1 in my code, the red light comes on, when I send LOW to that pin it goes off. But the relay never sends the 12v through the relay, the circuit side always remains open.
I have tried the jumper on high and low trigger, it reverses when the red light comes on and off, but the 12v circuit is never connected.
My actual voltage with my meter on the D+ from the arduino and on my pin output when HIGH pushed to it is 4.74 volts.
So the default closed circuit is always closed, and the default open circuit is always open. Since I see the red light change when I trigger it, it appears I am properly communicating to the relay. So what am I doing wrong? I have read other posts but could not determine my problem from them,