Ok, I've checked the wiring diagram that you kindly posted and things aren't adding up, the fuze usages don't correspond to what is on the back of my fuze box cover and I'm looking at the back of my hazard warning light and the colours of the wires also don't add up, I have a 1993 Torslanda, are they known to be so different?
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As for the buzzing, all the noises are coming from the flasher relay for the hazards/indicators, there is no other relay making noise and I can't find the seatbelt warning buzzer relay anywhere