Just replaced all four on the handles on my s class, did not know i had them until i came across a thread, may be fitted to other models too, have a look for a small round fibre optic bunch held in a white plastic moulding just below handle, real easy job to change (door card off),looks great now orange glow £20 each at dealers or just change the led if its blown or it might be the resistor also, either way it can be fixed for pennies if you can test and solder, any one needs help fire away