Originally Posted By: Johnny2Bad
Originally Posted By: SHOZ
Asian cars, at least Hyundai and Kia use the body for ground. Piggybacking a ground wire from the main body ground to the engine block is a good thing to do.
All vehicles use the body for ground, and have for perhaps a century. The only differences were whether the electrical system used a negative or positive ground; famously Volkswagen Beetles used positive ground, while virtually everyone else used negative ground. Aside from compatibility with various aftermarket electrical devices (car stereos, for example) there is no functional difference, but it's always easier to go with what has become an industry standard, negative ground.
There is always some form of engine to body ground connection in an internal combustion engined car ... otherwise the plugs wouldn't fire. It is possible that the ground could come in the form of a hard mount, but I don't know of any OEM vehicles that don't use rubber or urethane transmission or engine mounts, so there has to be some electrical connection, typically via a cable, somewhere. I suppose it could conceivably be from the battery negative terminal to the frame, as there is always a cable from that terminal to the alternator frame on the motor, which would complete the circuit.
I don't know of any specific issues with Hyundai or Kia vehicles (same factory, same production lines) but perhaps there is an advantage to a supplemental connection.
I meant the main ground goes to the body and is then distributed to the smaller grounds around the car at point of use.
Fords use the engine block as the main ground. Every load carries it's own ground wire back. My Hyundais use local body points for most of the grounds, those grounds not being used as control or inputs to the BCM.