Here's why:
* The frame acts as a common ground: The car's frame is made of metal and serves as a conductor for electricity. All other components (like the engine) are also connected to the frame, creating a common ground reference.
* Simplicity and Efficiency: Connecting the negative lead to the frame simplifies the wiring system and ensures a consistent ground path for all electrical components.
* Safety: Grounding to the frame allows for a safe path for any stray current, preventing dangerous shocks or electrical malfunctions.
While the engine block is also metal, it is generally not directly connected to the negative battery terminal. The engine block is grounded to the frame, creating a single ground point for the entire vehicle.
