my dad just bought a 2003 grand cherokee and the power windows and mirrors dont work along with the rear wiper and a few other things , i checked most fuses and replaced the window switch too , is there a main power block or something that could be bad ?

 

I remember seeing some threads when I first got my WJ about the wire harness at the drivers door. Something about one of the feed wires that can break there.

 

the harness between the door and jam is where my 99 gc wires broke.
There were 2 completely broke and a 3rd about half way through. It even
shorted out the speaker wire causing the radio to quit.

Pull the door panel and check for power at the main switch panel.