Great info there + snappics
Unless I'm mistaken, one of those ground connectors is for the dash LCD / CCM circuit, and causes the flicker that almost every C4 seems to have, post 17 years,
I don't 'mind' if a problem gets solved by accident (NOT Plug n Pray / Fully Automatic Assault Wallet), but I MUCH prefer seeing what was wrong - even if only a high impedance reading on the MM.