If you're referring to the white backlights, they should nominally pull 2.7-3.2 volts [blues draw same]. Amber and green are 2.1-2.3 volts, and reds are 1.8-2.1 volts.

A good LED driver is current based [constant current drive], and only supplies enough voltage to turn the LED's on.

A poor [but more common] LED driver is voltage based [constant voltage drive], and supplies as much current as the LED's need.

if the factory uses a CCD, then you can change the LED's and it won't care, it will just provide less/more voltage as needed.

if the factory uses CVD, then the LED's can become over/under voltaged, and will either not turn on (too low volts) or burn out (too many volts).

Going from white/blue to any other color, a circuit can be modified, sometimes. Going the other direction, you're usually screwed.