Electric checker - Blink relay...

Meal!

a question to the e-pros: I bought a used car trailer yesterday and picked it up directly. This one had a short circuit on the turn signal line in the right tail light.
After connecting the trailer plug to the V8 socket, there was no blinker at all, not even the warning flasher.

I thought I was sure the fuse had gone through - and I just drove home the few kilometers. I first checked the trailer there, found and removed cable damage, then wanted to change the fuse on the car - but it was intact!

However, even when the trailer was stuck down, there were still no blinkers. They didn't work until after I exchanged the flash relay, now they also worked on the trailer.

What's going on? And why has the 10A security not fulfilled its sacrificial role???

Who knows what?

Greetings
Jens

And have a good holiday!