is it illegel to change your coverage knowing that you might get into a accident?

If you have safety issues with your car, and you want to chane your insurance, there is no “law” that prevents you from changing your insurance. However, there are some insurance companies which will inspect your car before they will write your insurance. If you have an accident that is your fault due to the brakes not working you could have an issue with law enforcemtn for driving an unsafe car. That would be an issue with the police. However, there is nothing in the auto policy that says you must declare if you know there is a mechanical problem with your car. Of course, it is not a good idea to drive a car with bad brakes, especially in the winter time when things are much more dangerous. You may be better served by fixing your brakes before changing the insurance unless you can find an insurance company that is less expensive and you can then better afford to fix the brakes.