Forester SG Hazard Lights Not Working Due to Faulty Flasher Relay

Confirm this cause by listening for the characteristic mechanical 'clicking' sound when the hazard switch is activated. If the fuses are confirmed intact and the hazard switch has power, the absence of the clicking sound indicates the flasher relay is not completing the circuit. Testing can be verified by checking for voltage switching at the relay terminal pins; if the relay fails to cycle despite receiving a signal, the internal relay contacts have failed.

Sources