Problem:

Check engine light comes on with p0443 every 20 - 40 miles and stays on afterwards. I've narrowed it down to the power connector that plugs into the Purge Control Solenoid Valve. There is no voltage between the +/- connections. There is voltage when I ground the + connector to the body ground.

Question:

How can I troubleshoot the negative wire between the ECM and the power connector? IT isn't very accessible without ripping a lot of stuff apart. Even if I did rip everything apart how would I replace the wire? Is it possible to rewire the connectors? They don't look made for that.
Are there any other steps to take than replace the ECM and see what happens? I don't have access to another ECM.

Thanks