I'm planning to add side marker lights to the Acura RSX. I have two options: have them stay on with the parking lights or only blink with the signal lights (they won't turn on with the parking lights). There's a 3rd option where you can have them lit with the parking lights and blink. The only drawback is this option will cause irregular blinking; that is, the side markers will blink in alternation with the front and rear signal lights. I came up with a theory that uses relays to correct this irregular blinking, so no need for dual filament bulbs.
The idea is pretty simple. Utilize an 5-lead automotive relay to control the lighting of the side markers. Pin 85 will supply the power from the RED/YEL wire that will power the side marker as parking lights. Additionally, the RED/YEL wire will be connected to pin 87a as well to serve as a trigger point for the coil. Pin 30 will supply power to the GRN/YEL wire of the side marker. And finally, pin 86 will be connected to the vehicles GRN/RED or GRN/YEL (depending on the side) that will trigger the side markers to blink in synch with the front and rear blinkers. Pin 87 will be grounded, and the BLK wire from the side marker will be grounded:
The way it works: pin 87a and 85 will provide power to operate the side markers as parking lights (87a being the primary power provider and 85 as a standby to trigger the coil that activates pin 87). As soon as the signals are activated, pin 86 will be energized, completing the coil and grounding the side markers through pin 87 - turning them off in the process. When the blinkers are turned off, the coil is disengaged and the side markers will act as parking lights again.
So there you have it. Have your side markers remain on with the parking lights and blink in synch with your turn signals, the right way (at least in theory). I will test this out in December when I invest in my Dremel tool set and have time to install the side markers. EDM '94-'01 Honda Integra rear fog light install using the 2007-2008 Honda Fit combination / fog light switch (by gslowr) will be a pending project following the side markers install. Follow-up videos will be posted subsequently.
EDIT: 11/11/09 - after looking at the diagram again, the set up will NOT work without minor modification. I'll post a follow-up entry in December once everything is tested and ready for a visualInstall article.