I agree that the bulb failure sensor may not have anything to do with the cruise control.

I guess I should have said that you still have an issue with a light though they may all work.

I had a similar issue and finally fixed it by going through my assortment of light bulbs until I found two that pulled the same current draw when lit.

check this response from Art on how to check this circuit to determine where the problem is:
https://www.brickboard.com/RWD/volvo/1635949/220/240/260/280/step_one.html

The reason that I'm so adamant about putting the bulb back in is that in 1997 I purchased from my brother-in-law my first volvo 240, a 1989 which you see as my avatar.

unknown to me at the time, was the fact that the Check Engine Light (CEL) bulb had been removed by his mechanic because they could not get the CEL light to go off. Well after years of driving car and not knowing what I know today, the car started running really poorly. It wasn't until I took it to my mechanic and he pulled codes from OBD that we found out that the CEL light was missing.

So the moral to the story is find and fix the problems. Removing the light bulb is just a band-aid for something that is really wrong and needs addressing. Also, without the bulb there you won't know if one of your headlights is out until either you personally notice it, or a police officer pulls you over and gives your a warning or better yet a ticket for having a headlight out.

Just my 2 cents.

Matt