Sounds like your security alarm has been triggered. Take the keys out of the ignition, get our of the car, close the door and lock and unlock it WITH THE KEY. Then try starting.
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.
To make the hazard lights alternating flash, a kit called a wig wag is added to the flasher system. To have actual strobe lights, then a strobe kit with its own light has to be installed.
To determine if the hazard flash switch is bad in a 2001 Impala, check if the hazard lights activate when the switch is pressed. If the lights do not turn on or blink inconsistently, the switch may be faulty. Additionally, inspect the fuse related to the hazard lights; a blown fuse could also prevent the lights from working. If both the switch and fuse are functioning, further investigation into the wiring or relay may be needed.
The hazard lights on the Lexus LS 460 are typically located on the center console, near the climate control and audio system. You can identify the hazard light button by its red triangle symbol. Pressing this button will activate the hazard lights, which flash all turn signal lights simultaneously to alert other drivers.
To turn on the hazard lights in a 2003 Kia Sedona, locate the hazard light switch, which is typically a red triangle button on the center console. Press the button to activate the hazard lights, which will flash all turn signal lights simultaneously. To turn them off, simply press the button again.
A flasher relay interrupts power to the hazard lights making them flash. The relay can be a dedicated relay or it can be the same relay that operates the turn signals. Depends on the make, model, and year of the vehicle.
On the Lexus CT200h, the hazard lights are activated by pressing the red triangle button located on the center console, typically near the climate controls. When engaged, the hazard lights will flash all turn signal lights, alerting other drivers to your vehicle's presence. Make sure to turn them off when they are no longer needed.
If the lights come on but do not flash, replace the flasher relay. If they will not come on check the fuses.
The hazard flasher on a 2001 Toyota Camry is located under the dash, near the hood release. It triggers the hazard lights to flash and regular intervals to notify other drivers.
That is how the car communicates a transmission problem if you couldn't feel it.
On a 1997 Ford Aerostar, the hazard flasher is located on the dashboard, typically near the center console. It is a red button marked with a triangle symbol. Pressing this button activates the hazard lights, allowing all turn signal lights to flash simultaneously in case of an emergency.
it may be a loose connection on the back lights give a good firm push on the connectors