Turn signals and back lights work off and on on my 1980 Toyota corona

bulbs worn from vibration? water entry? loose wire ? loose connector? anythings possible after 30+ years. check the fuses and power distribution wires from the battery, then go to the lamps and verify power working your way back, find and verify grounds. you want less than .5 ohm at any connection, and ground the engine, body, and neg post. corrosion at the battery area canstart a plethora of electrical issues.

Electrical schematics can be made photocopy at the public libraryrefernce dept. be careful to get the one matching the wires by color, and note the month and year of production feb or jul.

connectors used to just wiggle loose sometimes back then and watch out for rheostats still in use, or wire insulation creeping away at the connector exposing it to metal parts in proximity. If your light and signal harness goes under the carpet leaving the luggage area and is under the floor carpet, damaging it can happen accidentally if you pierce it.

Lucas electrical is kinda tricky and corrections sometimes must be made for safety when you let the secret smoke out. disconnect power during repairs, seek an electrical tech who has english and european experience with lucas, or let the smoke fly ! be careful