Turn signal comes on solid when pressing brake

I have read a thread about this problem and have verified that all bulbs are working, I disconnected the trailer harness and I checked all wiring at the left rear turn light. Everything seems to be in order. I don't know how to check the flasher. Any advice on this or other possible causes? Also, is this something that could cause a serious pro

 

These links may be helpful:

https://www.tacomaworld.com/threads/turn-signal-comes-on-when-i-press-the-brakes.477901/

https://repairpal.com/when-pressing...passenger-side-turn-signal-lights-come-on-732

https://www.yotatech.com/forums/f116/turn-signal-comes-when-brakes-pressed-263508/

https://www.customtacos.com/threads/when-i-touch-my-brake-pedal-the-turn-signal-comes-on-wtf.47906/

 

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