1992 Delta lights issue

[talksteer]

When I received my car from Italy, I noticed that the headlights, turning signals, and brake lights all worked (so I could drive it) but the taillights, license plate lights, instruments lights, and side lights did not (but not in the dark!). I checked the bulbs at the rear, and found some defective ones, which I replaced, and then tested the fuses, which were ok, but no power was getting to the respective lights. So I sprayed contact cleaner into the fuse holders, and then the lights all worked. Success!

However, when going back to the drive the car on another day, the same issue occurred. Only when driving, and the car warmed up, with the headlights turned on, did the side light indicator on the dash would appear/came on, showing all the lights were working again...!

Any clues to why that is?

Thanks!