Hazards are controlled by the Body Control Module under the dash. It may be just a 5V circuit in the switch, so a relay that connects the input and output of that switch would achieve the same result as pressing the switch might do the job. You could test for continuity across the switch (remove the connector from the back and test away with a multimeter set to OHMS and look for zero ohms when the switch is active, infinite ohms when inactive).
A 12V relay will be fine, because you're not introducing 12V to the switch, the 12V in the name of the relay refers to the voltage that the coil needs to fire the relay. With an automotive relay, connect the output of the alarm (or whatever) to pin 85 of the 12V relay, pin 86 to ground (any bolt under the dash that holds the dash in place will do). Pin 87 connects to the active wire of the hazard switch and pin 30 to the other wire of the hazard switch.
That's assuming of course that the hazard switch is a single pole switch (I've never taken mine out to look). If it's not you'll need to take more care with polarity etc or you may be blowing more fuses.
A 12V relay will be fine, because you're not introducing 12V to the switch, the 12V in the name of the relay refers to the voltage that the coil needs to fire the relay. With an automotive relay, connect the output of the alarm (or whatever) to pin 85 of the 12V relay, pin 86 to ground (any bolt under the dash that holds the dash in place will do). Pin 87 connects to the active wire of the hazard switch and pin 30 to the other wire of the hazard switch.
That's assuming of course that the hazard switch is a single pole switch (I've never taken mine out to look). If it's not you'll need to take more care with polarity etc or you may be blowing more fuses.
