Handling difficult questions. It is important not to start responding to a difficult question before you have thought about the answer. Repeating the question and asking for clarification will help create some space for your thoughts.
Make sure all loads in vehicle are turned off, key is in the off position. Disconnect the negative battery terminal first then the positive terminal. When installing the new battery connect the positive terminal make sure not ground out the tool your using while tightening the positive terminal.
Disconnect the battery In some cars, especially those made before the mid-1990s, you can reset the check engine light by disconnecting the battery. Newer vehicles have a feature that will simply turn the light back on after the battery is reconnected if the car is not drained of electricity properly, however.