Ford Repair: knocking brakes, ford taurus, brake cable

Question
HI.. I have a 94 Ford Taurus. it has about 109,370 miles. It was just inspected and passed. I just had the front passenger side coil spring replaced. Since I brought it home from the garage, my brakes have been knocking every time I stop. Also the back right brake gets really hot once in a while and smoke pours out. My mechanic doesn't really give me to much info on anything. I've only had the car for a year, it was rather inexpensive and I don't want to put too much more money into it. Any ideas? Also, what does the code 45 mean for a flashing air bag light.

Answer
makes sure park brake cable is working free-is the rear pads or shoes
if pads be sure and check caliper bolts for binding they will rust and sieze up in caliper what is knocking front or rear-are they pulsating if so the rotors may be out of round and need machining either way all slides need to be free-look at fluid in master cylinder make sure it doesn't look contaminated with anything-discolored/residue floating or swollen rubber on cap if any of these things show up and fluid is contaminated it will make brakes sieze when hot but they usually release cold.