Interesting. Afaik there should be a ground on the rear tgv bolt, on the pitchstop mount, and one underneath on each head to frame rails and of course the starters
so i decided to perform a boost leak test. found out cyl 3 injector was leaking, i added an o-ring and the leak is gone. im sure water vapor would get sucked in through this leak when at idle in the carwash. we will see!