I have no idea where to turn. I just installed a new battery...yellow top Optima (sp). This is a pro street car. Big wire going from positive terminal to the master disconnect. Big wire running from other terminal on master disconnect along frame rail to Ford relay. I have juice at the backside of master disconnect, but NOT at where it connects to the relay. I have no idea what is wrong. I have looked for a pinch, no go. I checked ground from the negative terminal to the master disconnect, I have juice. However, if I move the ground to the roll cage, no juice.....I have a idea that this is a ground issue, but have no idea where to go....electrical is not my strong suit.

Not sure but doesn't sound like a ground issue. If you have power coming out of master disconnect and none at the Ford relay that sounds pretty straight forward. It's either the connections at one end of that wire or the other or it's the wire itself.

Is your chassis grounded? The main negative cable goes to the engine. From the factory there is also a small pigtail off the battery negative cable to the passenger side front fender. This provides the ground for everything except the starter and ignition.

Not sure but doesn't sound like a ground issue. If you have power coming out of master disconnect and none at the Ford relay that sounds pretty straight forward. It's either the connections at one end of that wire or the other or it's the wire itself.

Is your chassis grounded? The main negative cable goes to the engine. From the factory there is also a small pigtail off the battery negative cable to the passenger side front fender. This provides the ground for everything except the starter and ignition.

It is really strange. I had to move the ground cable to another spot. Maybe I should scuff up that hole a little. It is well painted.

Ground issue.....to much paint...preventing a ground. scuffed up the hole (inside it)..................works like a charm!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!