Dome light turns on when opening doors, but not when switched ON

My interior roof dome light turns on with the Door Opening setting, but won't light up when I switch it to the ON position. It used to work about a month or two ago. Any ideas? Blown fuse for the constant on trigger? If so, which fuse should be checked? Thanks!

 

probably the contacts in the manual switch. I've had to work on mine a few times

 

Thanks... I'll take a look and maybe lightly sand the contact points to see if that helps.

 

Those switch contacts are for ever getting dirty . If you remember cycle the switch numerous times a month .

Also the light circuit grounds through the hardware.