1999 C230 Courtesy Lights and Locking Signal

Are the courtesy lights (interior lights) and the exterior lights that blink and delay shutting off upon locking linked to the same switch/relay? If so, is there a remedy other than replacing entire domelight switch. Mine suddenly stopped simultaneously. The replacement domelight is rather expensive.
This is on a 1999 C230 but I assume may be common to other vehicles.