Primary Ground for Dash Harness?

[basstrix]

Do our cars have a primary ground lug for the harness under the dash? I can see a pair of heavy gauge wires near the fuse box, but can't see where the one, presumed to be ground, goes.

Recently, I noticed the tach needle moving when I press the brake pedal and want to confirm all grounds are making good contact. I also observe the tach signal on DAQ data that only shows up when on the freeway.

If any of you knows if/where the under-dash harness grounds and where that's located, I'd appreciate it. Pics are a bonus.

 

[midlife]

There are 2 main ground points: one on the far passenger side (single wire ring connector) and another above the glove box with 2 wires. Ground to dash is supplied by one of the dash connector pins.

 

[Moderator73]

Here’s pictures of what Midlife describes. If you’d like more pics let me know because my dash is out and I’m refurbishing it. I can easily snap more of what you might want.
Bob

 

[basstrix]

Thanks guys, much appreciated.