The current draw needs to be maintained for the flasher relay within BCU to function at the correct speed. Generally this means the use of CANBUS friendly LED alternatives. This being much simpler than using clumsy external resistors.
Please let me share another perspective Richard
Heat is the number one enemy or killer for LED's. LED life is directly related to temp. After market canbus friendly LED's bulbs are designed to mimic filament bulbs so may have a load resistor poked up the back. Typically the resistor will need to dissipate around 20w. That's an awful lot of heat in a tiny package. For the life claims manufacture's thermally mitigate the heat load using cooling fins on the bulb package, limiting the LED brightness or wattage and calculating life based on a typical shortish indicator duty cycle. However, should you ever need to leave your hazards on for and extended period, all bets are off for the poor old LED's....
This is my chunky 50w load resistor safely dissipating 20w through the metal body work. I checked it after fitting with the hazards on for 15mins. It was way too hot to touch and the temp was still rising.
![[Linked Image]](https://dl.dropboxusercontent.com/s/q4qzd0ame7ku96s/resistor.jpg)
