I drive my car Auto Brothers, and the engine light comes on sometimes it may not come on at all other times it comes on after 20 minutes other times after 1hour of engine running time.
Never comes on when I start it up even if the light was just on it won't come on.
Is it the ECM?
And if so will resetting it cause other problems in my car?
what do i disconnect the battery with wrecnh or pliers.
The cables looks like it's screwed in by a nut...

Help me Auto Brothers...

 

You'll need to find out what code the ecm is throwing. That will help to trouble shoot the ses code and find out what's going on. Some auto parts stores can and will hook up an OBD scanner, and will show you how the code is displayed. While you're at the parts store, pick up a Chiltons or Haynes repair book. It'll tell you how to do this simple test yourself plus list all of the ses codes that the ecm throws, and most of the repair proceedures.

Good luck