This might be relevant to some of you.
LED Turn SignalsI completely rewired the truck and put in dual filament switchback LED bulbs with white "filaments" for the running lights and amber "filaments" for the turn signals.
When I went to test it, I found the the commanded turn signal worked as expected, but the opposite side flashed at half the frequency. Only the front showed that behaviour.
I verified that both sides had the correct voltages on the correct pins at the correct times, so why was this happening?
I did install an electronic flasher unit for the low power LEDs, so that wasn't the issue. Switching to traditional incandescant bulbs made the issue go away, so the base wiring seemed to be correct (though the current draw for my lighting went from 923mA to 4.6A).
The issue turned out to be the switchback functionality, coupled with the lack of pulldown on the turn signal lines. There was a very, very short ground bounce relative to the turn signal line that triggered the switchback to turn off the running light, but did not have the current to power the turn signal.
The solution was a 10k pulldown on the turn signal wires to prevent the switchback logic from triggering.
