Grounds have been vexing car owners for years. My first new car, an '83 GTI, started having electrical gremlins. I got through to an engineer at VW in Troy, MI and he told me the transmission was grounded to the body - but the engine was not and they had problems with corrosion between iron block and aluminum trans case. I had one of the guys at the plant make me a short braided plated copper welding ground strap with soldered ends and holed drilled in each end, attached it between the cylinder head and trans case - problem solved.
2009 PBM G8 GT (Volant w/HSRK, Cortex, Homelink, Splashguards, Console Lid, Front Panel Mod, Glovebox Light)
2009 BMW X5 X-drive 30i (kidmobile but love getting my hands on it)
2007 Torrent AWD (kidmobile)
2002 Suburban LS 4WD (people/stuff hauler/winter ride)
2018 Jeep GC Limited (new wifemobile)
2018 Equinox (kidmobile)
1995 BBB Impala SS (SOLD but fondly remembered)