Linking headlights to interior light

[particlewave]

Originally Posted by geraintthomas

Well that's complicated lol!

I just wanted them to come on and off with the courtesy light lol. Going back to the original question, would that be easy to do? Rather than adding timers and photoelectric sensors? Literally just want the headlights (or parking lights) to mimic the courtesy lights.

Going back to basics: would a 12v feed with a diode from the courtesy lights to the side lights work? So that when the courtesy light turns on, the sidelights turn on, but when the sidelights are manually turned on, it doesn't turn the courtesy lights on.

If that works, that's literally all I originally wanted the only thing I'd need to know is the wattage of the diode. It would be a 12v diode, but what wattage?

Unfortunately, it's not that simple due to the side lights being positive voltage actuated and the courtesy lights being negative ground actuated. The circuit I posted won't work, either. You're not going to find a diode big enough. I was rushing.
You would need to use microcontrollers and relays like Meir is doing.

[geraintthomas]

Originally Posted by particlewave

Unfortunately, it's not the simple due to the side lights being positive voltage actuated and the courtesy lights being negative ground actuated. You'd need the diode relay setup that I posted for you.
That's still fairly simple, though. Just use a big a$$ diode to ensure it doesn't break down and cause issues. Forward voltage 20V or more, breakdown (reverse) voltage good and high (30-50V or something).

Watts = volts x amps, so just check the fuse amperage for the circuit you use the diode on and multiply x 15V.

Totally forgot about that relay! That's what I'll have to do

But I'll admit, got quite confused by how you work out the wattage. So, would it be 12v multiply by the amps of the sidelight fuse? :/