Can anyone list the grounding point for the ECM for the TBI powered trucks? Is the ECM grounded to the dash frame? Or does it have its own ground wire going somewhere else?

I'm having a problem that I believe is ground related, somehow connecting my headlights with other electrical issues including my ECM. I think the headlight switch is an important grounding point...but I can't quite understand it intirely, it is touching the metal dash which should ground it, but also has a black ground wire going to it (or from it to something else?)

Can anyone list the grounding points for:

1) ECM?
2) Gauges in dash?
3) Headlight switch?
4) Others?

thanks in advance, any other grounding tips also appreciated!