2001 Ford Taurus 6 cyl Front Wheel Drive Automatic 100500 miles
The MIL came on and I put the reader on and there are no codes. I then noticed that the MIL turns off immediately when the parking lights/headlight switch is turned on and the MIL is on again when the parking lights/headlights are turned off.
I am sure that this has nothing to do with the diagnostic/computer system. I am pretty sure that I should check all the wiring connectors/relays and possibly trace all the wires back from the MIL to see where it is getting juice from.
Any ideas? Has anyone seen this before?
Most likely, you have a bad ground. Check along the wiring harnesses. At several points, you will see wires exiting the harness and bolted to the body. One of these is broken or corroded. When you turn on the parking lights, the system is grounding through the light circuit. Check especially around the headlight mountings where there is a ground on each side of the car.