Alternator testing: Autozone Fails; O'Reilly Passes


Active Member
Jul 25, 2003
Springfield, MO
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2000 Mustang GT alternator. Sold the car for salvage and kept some parts off of it to resell.

I drove the car a total of about 4 miles before it broke, but I do not remember the battery light coming on. I have no reason to believe the alternator is bad, but wanted to have it tested before I sell it.

I've went to 2 autozone stores and it fails at both of them (two times at one store and one time at another).

I've went to 2 O'Reilly Auto Parts stores and it passes at both of them.

I mentioned this to the guy at the last Autozone store and he made a comment that the machines are the same exact machine (and made it sound like I was lying to him).

Not trying to start anything, just wondering why the stores would differ and is there another way I can test it? I don't want to sell a bad alternator, but I don't want to junk a good one either.
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There's nothing worse than aut
Founding Member
Aug 23, 2001
Westland, MI
It fails at Autozone because it's not from a Honda.

All kidding aside, I worked at Autozone for a few years, and the employee training/machine upkeep was nonexistent for those machines. For what it's worth, I had the exact scenario happen with an alternator from a 95 Sable, and it worked fine on the car.