I throw this quickly together to give an idea but very minimal key parts. This simple circuit allows the STEP Light to turn on via the existing porch light switch located at the entrance lower left area. Now the step light works in either manual mode by way of porch light switch or automatic mode with electric step function. I used quick connector on the ends that way if for any reason i wanted to remove it, i could do it easily.
1. 15amp Diode Axial Schottky Blocking Diodes found on Amazon
2. Butt connectors
3. fuse holder (5 amp fuse or smaller)
4. heat shrink
5. liquid tape
6. Spiral wrap (To protect the diodes overall all)
1. quick circuit sketch
2. final circuit made
P.S. I did this similar circuit for the front daytime running LEDS in the headlight bezel and that turned out awesome very satisfied. I use the circuit that operates the front cap SPORTSCOACH Illuminated logo to now also turn on the 16 front LEDs at same time. Now i have night clearance lights in the front area when ever i want and they accommodate the white underglows nicely. If you recall these small headlight bezel LEDS by factory design only turn on when ignition is on, but not no more
Sorry i missed any details but i can help answer any questions.
Just a guy