It would take quite a bit of information to answer this question for you specifically, which we don't have, but in general consolidation won't make a difference.
On time payments (or the lack of them) is the main determinant of scores. If you have 13 loans and pay one of them late repeatedly, your score will suffer greatly. If you have 3 credit cards and like to pay one of them late every month, but a different one, your scores will suffer.
In order, the biggest problems are bankruptcy, foreclosure, short sale, deed-in-lieu, judgments, charge-offs, collections, late payments, and balance to limit. Paying off a credit line will work on raising that portion of your score related to credit utilization, but it is usually the smallest contributor to score for people with low scores. Their problems are usually charge-offs and collection and then lates.
You might want to take the on-line credit repair course from Henley http://sumnerrealty.com/content/article.html/2711606/creditreports