hello,
Last weekend was not the best weekend for my truck, auto gearbox quitted, brake lights quitted, and the hazard warning as well, the second time even.
I had it repaired, the hazard warning, even I didn't know how, it sort of just started working again when I was goiing through the regular flasher and fuses.
beeing a '89 F-350 my hazard warning is at the pass.side under the glovebox.
any advise is well appreciated.

ps it might have something to do with the brakelights, they stopped working as well.

 

i would replace the flasher .they do not last forever.
and if you have LED lights on the truck, you need a special flasher for LED lights.

i read the post where the trans dumped all its fluid, but was not able to respond at the time.
what happened to it?
if the breather vent is clogged by a big, that will cause the trans to pump itself out.
so the trans may still be good and just have a plugged vent.

 

If you have a hook-up for trailer lights make sure all of the connections are secure. When I bought my truck I had trouble with the brake lights and tail lights because the previous owner had installed a hook-up for trailer lights with wire nuts!