Cadillac Repair: interior lights problem., amp fuse, cadillac fleetwood


Question
hello i have a 1980 Cadillac fleetwood
and none of the interior lights work at all
the only thing that works is the radio and blinkers
what would you think the problem is??
the fuses are all good i checked every one of them

Answer
Does the interior lights operate if you open the passengers door ?.

Do they work if you turn the dimmer control ring around the head light switch ?.

On the very top of the fuse box there is a 5 amp fuse. Check it with the parking lights ON and by turning the dimmer control ring around the head light switch and see if the instrument panel lights work.

Your POSITIVE that the 20 amp fuse just above and to the left of the flasher that is plugged into the fuse panel is OK ?.

Prior to this problem did the interior lights remain ON for 15 or 20 seconds AFTER you exited the vehicle and shut the doors ?.