Okily Dokily, I setup my Keypower DC-DC PSU and figured out the connectors... My car electrician expert guy helped a bunch too.
You need to run a wire from your battery's (+) positive and (-) negative. That's what you'll attatch to the (+) and (-) on the PSU.
Then you'll need to attatch the (G) ground connector to the frame of your car... meaning a screw, nut or other bolts most attached to the metal fram likely found under the cars carpet. (These things are all over the place so it shouldn't be too hard finding one)
I assumed the (G) and (-) were the same, but from what I understood the psu needs a direct run to the (-) negative of the battery, AND a ground to avoid any surges (and or explosions
) When I tried it the first time assuming that, the PSU sparked and sent tiny fireworks into my trunk.
It's been working for me this way ever since i got the unit. Plus I don't think anyone with a $170 dc-dc psu would want to risk blowing the unit, or even worse damaging the computer components.
Hope it helpes,
SuperAJ