PA. Penalties on child not on car seat?

Does anyone know the penalties for parent(s) who doesn't properly put their child in car seats. I tried to look it up but I can't find where it states what the penalties are. I have a 4 year old son. HIs dad doesn't use a car seat and sits him in the front seat of the car. I have pleaded with him to please put him in the car seat in the back instead of the front seat. I even told him that he is risking our son's life by not properly securing him in the car seat where he belongs. If and when I do, he just agrees with me but does nothing about it. I am at my wits end and scared to death that one day (god forbid) his stupidity and lack of respect for the law will cause lives. I was even thinking of talking to his next door neighbor who is a cop to have a chat with him about not putting our son in a car seat. I know I'm wrong about this but I'd rather be wrong than lose my son because his father won't take a minute to properly secure him in the car.