I had a brake light so I stopped by the mechanic and they said I need pads, rotors, and a brake caliper.

How do you inspect a brake caliper to determine if it needs to be replaced?

 

Hmm... I wonder where Pmohr has been?

But usually you can tell when a brake caliper needs replacing when it seizes up, like if you release the hand brake and the foot brake and look at the brake pads outside, their should be a small gap between the rotor and the brake pad on inside of the caliper.

Also another way to tell is if you have excessive screeching when you are not braking and just letting the car roll along without stepping on the gas, like a while ago I had my rear calipers seize up without me knowing and when ever I moved there was a LOUD screech but that was coupled along with worn rotors and pads.

 

I would definitely ask them for the reason they say it's bad to make sure they aren't trying to make for money off of you. A siezed piston is the most likely failure. If you jack up the car and can't turn the wheel by hand, then you've got a problem.

I change rear pads not long ago, and noticed that one of the dust boots was twisted pretty good. The rear piston rotates as your pads wear and if the boot sticks to the piston, it could rip.

 

The brake light ON means your brake fluid level is low. I hope you're not being taken for a ride by your mechanic.

 

I guarantee that they are taking you for a ride. Replace the pads and your brake light will go off, it comes on when the fluid gets low in the reservior. Unless you have a leak in the system (unlikely) your brake fluid isn't actually low, but having pads that are extremely worn will cause most of the fluid in the system to be down in the brake lines and calipers (because the pistons have to extend out so far to press the pads against the rotors), instead of up in the reservoir.

 

All four of my rotors and pads were shot to hell, and my brake light wasn't on. I'd say like everyone else checke your fluid.

 

I just did this repair myself on my maxima this past weekend. Front/Rear pads/rotors, and my rear calipers were frozen so i replaced them. I could tell (aside from the dealer telling me) because it was rusted to hell, the pads basically broke apart when I removed the caliper too. You could try compressing the caliper too, if it doesnt budge then its frozen up. They will probably charge you $1200-$1500 when you can do it yourself for about $400 (after returning caliper cores) if you have all the tools already. Cost me about $600 since I didnt have tools or stands, but def worth the investment in the long run.

 

Assuming he's working on the front, then yes, you could do that. If the rear, they need to be turned in.

The pistons in the rear calipers do not 'rotate as the pads wear', they push straight out, same as the fronts.