I'm trying to control my headlights with my Arduino and a LDR. For this I will use the Arduino as a middle man between the lights switch and the actual lights. The switch has three positions OFF / DAYTIME LIGHTS / HEADLIGHTS. The switch itself is a potentiometer and has 3 cables: 12V, GND and the signal one. The Arduino then would read which setting is chosen in the switch, decide what to to do, and send the signal thru this cable.
The problem comes here. The Arduino, as far as I know, can only handle <= 5V. So how am I supposed to read the switch, and then send a signal back to the car? (I suppose that these signals would be around 12V or so).
Sorry if I'm not explaining so well. Not very experienced in electronics.
I have measured the voltages across the three cables (WHITE/GREEN/BLACK), assuming black as ground.
When engine is off:
White = 23-25V
When engine is on:
- Switch == off
White = 28.5V
Green = 30.3V
- Switch = daylights
White = 0V Green = 30.3V
- Switch = headlights
White and green = 0V
From this I wouldn't know what to do. Thought the switch worked like a potentiometer but I think I am wrong.
Also I am trying to find a logic answer of why both white and green have 0V when the lights are switched on.
I found the part online, and its name is "WELLS SW6250", a combination switch. I thought that, because of the white and green cables going 0V when the lights are turned off, that there might be another cable coming from the square part of the knob, where there are other connections.