Why my 1998 windstar van instrument's "service engine soon" light always on and how to turn it off?

I made a wrong measurement that I measuring door lock source line right before the motor unit. I measured its voltage,connecting one line to positive the other line to negtive, than heard a currents shortcut noise.then I immidiately stop connecting. then I start engine check it to see is there anything wrong.Since that time the "service enging soon" is always on when turn on that enging..Till now it has 6 months. nothing happen execpt that light.





Once a time I drove to auto company to check it. He use an instrument probably is ''OBD II " to scan it . he said maybe it is caused by oil tank's vapor or gas tank cap was't locked properly. We checked cap it was locked properly.But I am very sure it cause by my wrong measurement.


Is the generic electronic module same part as powertrain control module? If they are two different parts.Where are their locations...|||If you goto Advance Auto Parts or similar, they can check the code that turned the light on and turn the light off at your request.