I am new to Toyotas but just picked up an 83 which had the same problem. The problem turned out to be the light on RF fender shorting out.
The best I can tell the PO put in a big fuse and burnt the wiring from the fuse box toward the parking light relay under the dash. I have been tracing wires and fixing this problem for about 10 days off and on. I had to completely untape the wiring under dash to get it fixed and after tracing wires and looking at the manual I rewired the relay and it works. It might be a good idea to check all of your clearence lights to see if one is shorting out. Hope this helps.
