I should have noted in my PM to you that I'm working with my dad on this project (he is an electronic genius!) and the current LED lights were built by someone also with knowledge of electronics. I was interested though to see how you built yours.
The LEDs I will be using are the square "4 leg" Superflux type, soldered to normal prototyping stripboard
Also worth noting with regard to the brake failure warning light, the "ECU" for this is built into the drivers side rear light, so once you'd gutted them for the LEDs, you'd lost this part. There is a wire you can earth to the car body to turn the warning lamp off, or like I have done, simply remove the bulb from the warning light
