I’ve been working on adding new wiring EMI shielding for my knock sensors wiring on my 95 sc400, i have a drain wire set up to a chassis ground point but wondering if it needs to ground to the engine block, can/should it ground to both? or only one specifically? i was never sure about the factory (it’s supposed to be shielded from factory, right?) -shielding’s ground point and can’t really figure it out. Testing the existing one i’ve discovered it has no continuity so it’s not grounded as far as i can tell. I’m not super experienced in electrical work, trying to do good research and just want to make sure its done right so i dont have to worry about it again.