Confusing electrical issue - 2006 DTS Lux III
 

The illumination bulb/diode (whatever it is) for each of the switches on the right rear passenger door are not operating. The mechanism each switch controls works (window, lumbar, heated seat), but there is no illumination behind the switch. All other switches in car have the required illumination.
Any experience with this or similar issue?

they do burn out

but u can change the other back door switch and put it over there if it works
then its a bulb

if it does not then its a wiring issue