Take another look at the original sentence:
You wanted to fix it this way:
When you have two main clauses incorrectly joined together, one way to fix the problem is to subordinate one of them. Because is a subordinate conjunction that will do this job. You must remember, however, that when because follows a main clause, you should not use a comma with it. In fact, 99.99% of the time, you do not use a comma before because.
You might want to consult the rules for fixing comma splices and fused sentences.