30 amp fuse keeps blowning for pcm

Unfortunately the circuit will have to be traced using a good volt/ohm meter and wiring diagram to see if the circuit is shorting to ground, the computer has an issue or something reporting to the computer is shorting to ground. If you need a wiring diagram or an explanation/overview on how the system works and feel confident to check out the problem your self, there is a company that independent auto repair shops "buy" their information from that offer a very reasonable service to do it yourselvers. You can get a one week subrcription or year subscription very cheap. The information is year make and model specific repair procedures, service bulletins, component locations, wiring diagrams ect.... great quality information same as the professionals have ,much better than generic workshop manuals from parts stores, much cheaper than the factory manual try http://www.eautorepair.net/Marketing/Default.asp?VID=125669 and get an online repair manual subscription.