I bought a used Prodigy brake controller (probably few years old, the display is red, not blue like the new one). Everything seems to be connected properly, if I use the manual trigger, it will display n.c. (which is normal, no trailer is connected) However, I'm not sure if it is supposed to, but when I depress the brake pedal, nothing happen on the display (still without trailer connected). Is it normal? Is it supposed to display something, like voltage? Or do I really need to connect a trailer to test it?

 

Found the answer by myself: the stop light wire (the red one on the brake controller) was not connected properly to the green wire from the truck harness. Now when I step on the brake pedal, I see the red dot, so now I think it's working as it should.

 

That is what I was going to say, there should be a red dot when no trailer is connected.