Will low grades for a minor on my trascript affect my chances of getting into grad school?
If I understand you correctly, you have been doing rather poorly in your current major but will change to another where you expect to do better. Assuming that you do, in fact, do very well in psychology and all of your later grades are better than your earlier ones, you may be ok. You can explain that you were ill suited to your first choice of study and changed, and now you are doing fine. 

That would be a winning position for some, but not all, institutions, but you have what you have in your background. Make the most of your future, of course, and work harder, if necessary, to be a success. 

Short story: Not a great position, but not necessarily a losing one. Make the future count as you can't change the past.