Well I was trained as a German car and truck mechanic back when they ran a ground wire to every component for reliability. Yes I use frame grounding points but I still don’t consider it a reliable circuit unless every component has a power and a ground wire. Too many problems from bad grounds with the amount of plastic, rubber mounts, thin metal and protective coatings as well as loose connections. I had to jump a brand new Ford F-350 Diesel yesterday that had the keys inside with a shorted trailer plug that had run both batteries completely dead while parked with the keys inside and electric door locks locked. The owner had tried to use his jumper cables to back feed the power wire from the trailer to get enough power to open the doors so he could open the hood to jump the batteries unsuccessfully because they were so light gauge. I got mine and attached the positive cable to the starter solenoid and had him attach the negative to the frame still no connection. We had to find the ground bolt from the engine to the frame cable in order to get a good connection as apparently the frame is coated with a nonconducting material. Seems the more problems get fixed, the more problems the fixes create. I can easily fix and troubleshoot a two wire system not as easy for me with other systems so I guess I’m a little prejudiced.
