What about Lexus license plate lights? Well, those are not LEDs. Those are actually CCFL tubes, which is why trying to recreate that color with drop-in LEDs is so difficult. It turns out too blue.
Best solution? Use what LCD TVs use in place of CCFL tubes: pure/natural/neutral white LEDs.
NOTE: "Warm white" is not the same as natural/neutral white. Warm white is designed to mimic the yellow color of incandescent bulbs.
Compare. Left is my custom natural white LED board vs. a drop in "white" LED on the right.
Stock 194 incandescent bulb on left, drop in "white" LED on the right.
Start out with two protoboards cut about 40mm x 10mm.
Extra step: dip in liquid tin to tin the copper, makes it easier to solder and prevents them from oxidizing.
Solder OSRAM PLCC-2 white LEDs in series, sets of 3. Two sets in parallel. 12V--(>|)---(>|)---(>|)--Ground--(|<)---(|<)---(|<)--12V
Wired up. Not pictured is a 194 connector at the end.
Comparison. Incandescent bulb, natural white board, high power cool white LED board.
A word on mounting. The board will simply sit behind the lens of the license plate light. There is enough of a gap where it will sit normally. Use a dab of hot glue to help secure it, then replace the lens as you normally would.
PS: If anyone wants, I can order 40 of these in bulk. Using different brand LEDs, but more of them and will run in the $5/each range.
Edited by Serge, 29 December 2011 - 07:14 PM.