93 240 wagon. On the cluster, to the right under the fuel w/t gauge is a tiny hole w/ a button in it. It does not appear in the owners manual. Whats it for? How does it work? Etc.

 

possibly an aftermarket alarm....

 

Changing the time on your clock? (I'm just guessing from the description, I have never seen a 240.)

 

Maybe it is the button to reset the service light?

 

I have always wondered that myself. I have taken a pen and pusshed it many times but it does nothing. This is on my 93 244

 

On the 740/940 it is for resetting the Service Light which comes on every 5,000 miles. Then when you push it, it resets itself for another 5k... If the light is not on, and it only stays on for 1 minute afer each start, it will do nothing whenthe buttonis depressed.