For those who have attempted to replace the license plate globes with LED's, you'll know that majority of "non-CANBUS" ones do not work, and even those marked as error-free do not necessarily work all the time. The reason for this is that the car's computer checks the current/power flowing through the license lights, if it is below a certain threshold then you'll see a warning on your MFD which can get quite annoying.
My solution is to permanently solder a resistor onto the casing. It is essentially the same thing as buying load resistor kits but at a much cheaper price. I bought each resistor for $0.40 each. This entire solution cost me less than $1!
First things first, before I tell you what resistor to buy it is important to understand the basic physics of what you're about to do.
The stock T10 globe is 5W.
Each 5050 LED consume about 0.2W (assuming 12V power source), so the 9 SMD 5050 LED globe like the one I used above may draw up to 1.8W (9 x 0.2).
5W - 1.8W = 3.2W difference from the stock globe! Now we would like to look for a resistor to fill that 3.2W void. We know pretty damn sure that the computer isn't checking for exactly 5W as bulbs will not always draw the exact advertised watts. I made a wild guess that maybe it is checking 50%, or 2.5W.
I selected a 56 ohm resistor (5W capacity) which would draw about 2.57W. If you must know the calculations...
12V / 56 ohms = 0.21429A
12V x 0.21429A = 2.57148W
Ok, so 2.57W resistor + 1.8W LED globe = 4.37W total power!
I tried the resistors without any globes and saw no MFD error, which means the threshold is below 2.57W. That's good. This means I can put in anywhere from 1 to 12 5050 SMD comfortably, but it is normally safe to exceed the 5W. I'd say maybe up to 6W or so is safe? That gives us up to 18 SMD's. Not sure if you'd want them that bright anyway.... if so, just pick a resistor with a higher resistance and you'll be able to put higher capacity LED's.
Resistors do not have polarities so it does not matter which end gets solded where. Make sure there is enough clearance from the resistor to any other part to avoid it melting any of the interior components.
The resistor draws about 2.57W and I chose a resistor with a 5W capacity to make sure I have accounted for fluctuations in the power source. Car batteries are not precisely 12V. Some sources claim an average of 12.6V or even as high as 14V!!! It is wise to pick 5W capacity versus 3W for this reason. Plus your resistors will last longer if you keep the running power at around 50% of the rated maximum capacity.
Also remember that by soldering the resistor, you're restricting yourself to using LED's. DO NOT put regular 5W globes on them as it the computer might shut down that entire circuit thinking it is defective for drawing too much power. It is also a good idea to remove the resistors should you decide to sell the car as it is easy for future owners or non-electronics savvy mechanics to just replace them with regular globes!
Disclaimer: I am not responsible for any damage this may cause your car. Do this at your own risk. I have done electronics at university over a decade ago so I'm not exactly an expert on this, but after some brushing up, I am confident my calculations are correct!
Hope this helps anyone. Each resistor cost me $0.40!