1. Open the hood of your vehicle.
2. Locate the battery.
3. Look for a wire that is connected to the negative terminal of the battery and follows the chassis/frame of the car.
This wire is usually black and may have a ring terminal or a lug at the end. It is important to note that the location of the ground engine wire may vary depending on the specific vehicle. If you are unable to find it, refer to the vehicle's owner's manual or consult with a qualified mechanic.