diode, led strip

I have an LED Strip on my mirror which comes on when my running lights come on, the source is from the orange lights in the headlight..I want them to flash also now when i signal So the Orange bulb in my headlight has 3 wires, 1 for running, 1 for flashing signal, 1 for ground. Im gonna take both Running and Flash and run it to my POS on the LED Strip. how can i use a diode in this setup to not have any backfeed? and what kind of Diode/Rating will i need? Will i need any resistors or anythign? Thanks for all help guys This is a 2008 Mitsubishi Raider

Do you have any idea of the current needed to power the LED strip?

Is the orange bulb dual filament, or is it full on else off when flashing? If the LED strip is NOT high current (relative to the bulbs/s), then the strip can be connected between the 2 wires (anode/+ve to running, cathode/-ve to the flashing wire) if you don't mind them flashing out of phase.    Similarly but for higher current LEDs - the flashing wire energises an SPDT relay; the "running" wire going to 30; LEDs from 87 (NC), flashing wire to 86 & 85 to GND. Hence when flashing, the power is disconnected. If you want flashing when the running is off, then you need a stop-flasher (or reverse-flasher) circuit (typically a DPDT relay for each side).   (Or maybe a bridge-diode circuit...??)