Where are all ground wires?

@glentrs,

I think you may find this useful: Free Car Service Manuals from Operation CHARM Scroll down to GMC, then scroll down to 1994 or just click that blue 1994 and scroll down to your model, the files are zipped, extract them and you should then be able to access them directly on your computer, if you CAN'T because of say, windows' restrictions etc, you can just view them on-line instead or you can browse the folders you extracted with an image viewer and find all the wiring diagrams along with colors, etc. If you need help reading and interpreting the diagrams, THIS page has that covered.

You might also find THIS video helpful. (He goes over 1995 - 2002 GM OBS Truck Wiring Harness Grounds and Where to Find Them using the service manual and then shows actual examples in the video.

If that doesn't help holler and I or someone else, will probably be able to help you more.

Good Luck!