I have an 87 XJ and I have come across a leak in the cowl area. The leak has been elusive and I'm gettin annoyed!! I have traced the leak to somewhere above the ECU. There is a bracket above that water seems to be traveling down. The water travels down the bracket , down the ECU and onto my drivers side carpet. I have sealed every seam you can imagine!! Please someone help me!!

Does it leak when it rains or only when you wash it? Try using a garden hose to apply water along the bottom of the windshield and see if it leaks. There are also quite a few "penetrations" of the firewall for hoses and wiring. Any of them may leak.

It leaks whenever it rains or water is applied to the cowl area. I have sealed every firewall cutouts for wires, fusebox inlet, etc.

Did you look in the cavity where the wiper motor is located?