Celica Forums Classic Generations 5th Generation Celica Hazard lights mistery

Copy paste from my post in a different part of the forum, really need to resolve this issue as the car will fail APK ( Dutch equivalent of MOT) without working hazard lights

Last week i came across a 1992 T18 1.6 sti.
It was not expensive, only had 1 issue, the hazard lights do not work. Easy fix I thought, I guess I was wrong.

I am trying to fix this, but I am stuck. I replaced a 30v fuse under the dash that looked corroded. nothing changed. The blinkers work fine, just not the hazard lights. If I press the switch then the turn signals stop working. If I unpress the hazard switch the turn signals will work again. horn works either way. The turn signal flasher is not broken I guess, as they work just fine without the hazard light switch pressed. I removed the hazard light switch and the turn signals did not work, but the horn did work just fine. Then I replaced the hazard switch and the problem was still there.

Does anyone know what I can do next?

A random idea:

confirm that you have the correct size fuses in each position. Your lighting may her be getting enough power to handle the requested demands. This could also be related to something else on the same circuit demanding more power than what can be supplied.