my mom has an 02 blazer and recently it started making this squeaking noise when she is backing up. any ideas on what this could be??

 

Is her foot on the brake?

If so, get a brake check. Some places charge a nominal amount yet take it off the bill if you get the work done. Place I used to work for charged $15 for a brake inspection. That meant taking hte tires off and micing hte rotors.

 

My brakes on a car of mine were doing something similar to that. I took it to firestone and they couldn't find anything wrong with the brakes. They didn't charge me anything. they said that they would only charge if there was something wrong with the brakes. So maybe all firestone places do that or just mine, I don't know. But I do agree with the suggestion of a brake check.

 

If it's a squeal that doesn't change, then it might be brakes.
If it's a squeak, squeak, squeak that get changes with speed, then it might be a "U" joint on the rear driveshaft.
If this only happens in reverse, I'd be sure to check the "U" joints.

 

its not the brakes, shes had those checked a couple of times before, i will tell her to have her u joints checked out. thanks for the responses

 

If she's always backing out of a parking space with the wheel cramped it could be the power steering pump.