I have the same problem (2001 Taurus). I pulled the connector blocks from the fuse panel under the dash, and could not see any obvious isses (no bare wires, no way for connectors to touch. Symptoms:
Check engine light on. Goes out if headlights are turned on.
Occasionally the "Door Ajar" light comes on, and then the door locks luck/unlock rapidly. This is intermittant and clears (for while) when a door is opened and closed.
Is it possible ther is a bad ground. And if so where would I look look?
I have cleaned the negative battery post as well.
Sunday, June 1st, 2014 AT 4:02 PM