The hazard switch itself is bad. The flasher module for the turn signal is built into it. Replace it yourself for 100 dollars(cost of part).
Try turning the hazard flashers on and off a couple times, see if that starts your signal lights working. If so, replace the hazard switch/module.
What year is your Impala? 2001
try replacing all sets of fuses for the hazard and the tail lights.
if you mean: "why do hazard lights flash when brakes are on", then the answer is because vehicles are equipped with a hazard light relay that supercedes the brake lights. This way, slow moving vehicles can operate under hazard lighting.
Turn signal flasher?
If your 1999 Ford Expedition has turn signals that do not work but hazard lights that do work, it is likely that you have a fuse that is blown. You might also have a wiring issue including exposed wiring.
Lights or signals fits this 'fill in the blanks'-type question..
Is the hazard lights button not on top of the steering column ? The switch for the hazard lights on my 1995 Ford Explorer is part of the multi functin switch ( turn signals etc. )
If the turn signals on a car works but the hazard lights do not there may be a problem with the flasher switch. The flasher is located in the steering column, and a damaged unit can cause the lights to stop working.
Make sure hazard switch is pulled all the way out May be a problem in thw steering column
hazards and turn signals have separate flashers. replace flasher for turn signals
There are 2 separate flashers.jd