chevy duramax wont start
working on sons 2005 chevy duramax diesel, he pulled it in shop to clean it out and then it wouldnt start. , with key. when you jump the starter with screwdriver it cranks fine and starts. i thought the terimals on starter solenide were loose and ended up replacing starter and it still wont start with key, but ok when you jump starter terminals. so could the saftey start switch on the auto trans be causing this and could anyone tell me where abouts it is on the trans. there are several possible switchs or connections..just not sure which one , it is a 3/4 ton 4wheel drive , thanks in advance.