What is this part? Front right of engine bay between battery box and radiator. I have the dreaded not charging light on, changed alternator after checking and getting 11.2 out between output post and negative battery terminal and engine bay ground. Leads are checked out ok, same issue with new alternator, both batteries I have for this car are tested good, with high CCA. The 4 pin plug to the alternator is clean. Is this in the charging/regulator circuit?