If you're having issues with your brakes, the culprit could be the guide pins, but a careful inspection is the only way to know for sure.
When you're changing your brake pads yourself, part of the job will be removing the guide pins. But what happens if you put the pins back improperly? Then you could experience noises or problems stopping. The brakes could stick or grab when you're driving, or you could hear a grinding noise if the calipers aren't meeting the rotor at the proper angle.
So how do you know if the guide pins are at fault? You'll need to inspect the brakes like you're about to change the pads. In fact, it's a good idea to check the pins whenever you're changing the pads yourself. Lift the car, remove the tires, take the caliper off and look at the caliper housing. See those pins at the top of the housing? Those are the guide pins. Most cars have two guide pins with a rubber housing surrounding each [source: Dan's Garage].
Problems to look for include caliper pins that are corroded, or ones that aren't properly lubricated. Also, the pins could be stuck in the rotor or they won't go in all the way after the pads have been replaced.
The pins should be easy to take out with a screwdriver and a few light taps from a hammer. Caliper pin removal tools are also available at auto parts stores. If the guide pins are really stuck in there, or if they're rusted in place, you may have a problem on your hands. In that case, you'll need to find an experienced mechanic to discuss your options.
Next, let's discuss the proper way to re-insert the guide pins.