Turn Signal Problem -- All Lights Flash At Once

My 1989 Olds 98 Touring Sedan flashes its signal lights all at once when, with its hazard flasher quite clearly off, I signal right or left.

Immediately beforehand my interior lights had been left on for about forty-five minutes.

Any suggestions.

sound like the wrong light bulb installd in the rear light or shorted bulb
check it out and report
thanks
michel

The problem was temporary, self-correcting on my restarting the car the next day. I don't know why yet. Presumably. I had an intermittent short.

If that the case you have shorted bulb, check the rear bulbs ,i have seen it happen
michel