First off, I'm new here - found this site while researching to figure out why my circuit isn't working as I expected. I appreciate any help you can provide...
The picture is the wiring diagram for the headlight circuit on a custom car I built (http://www.britishv8.org/MG/RobFicalora.htm). I'm trying to add a bi-color LED (using 2 legs of an RGB LED) where green will indicate low beams on & blue will indicate high beams on. The LED is a common cathode LED.
Instead, what I'm getting is green when headlights are turned on; both blue & green when I flip to high beams; both blue & green when I flip back to low beams; LED off when I turn the lights off. The headlights themselves work properly and the low beam turns off when high beams are turned on.
Ignoring the LED wiring for a moment, note the headlight wiring & relays 2 & 3 in particular. While troubleshooting, I noted that the wires between pins 87 and the headlight bulbs show +12V. When I designed the circuit, I was thinking of those wires as "grounds" -- being passed through the relays when energized. In retrospect, it makes sense they'd have 12V on them because the headlights natually connect the + & - sides. Is there anything wrong with how I've designed that circuit?
Do you see what would cause the LED's not to work properly?
NOTE: I didn't draw in the resistors, but I do have them wired & soldered to the LED legs. Both the blue & green sides of the LED work properly outside of this circuit simply connected directly to the battery.
Ok, i'm not getting very far very fast. I tried the capacitor with no luck. And, I'm getting confused by the fact that pins 86 & 87 have 12V on them when the headlights are off (which makes sense given 85/86 is a coil so 85 passes thru to 86 & since the headlight has a filament ("A") which connects the 12V source to the "ground" side that goes to 87. Not sure if one of those is causing a problem? I've included a simplified diagram of just the low beam headlight wiring below for easier reference...
Oh, and headlights are standard automotive halogen bulbs (not HID bulbs).