No, notthat I know of, but to work at a local shop you will need to know a lot more than wiring. Go to B&N and pick up some literature on CA&E, and then do a lot of research on the particular wiring schemes in different makes of cars. Better yet, go to your wishful future employer and ask them what type of knowledge and skills they look for in an employee.
There is a cert that some installers get, and if you couldget that, it would probably help a lot, I cannot remember the name of it though, I think it is something like MCEP.