hi, im installing a new deck in my 1988 trans am GTA, but when i look at the wiring harness comming out of the trans am, i see two black wires with light blue stripes on them, are any of these the ground wire, the guy that had the car before me already cut off the connector. from the wiring diagrams i got from this site, it says black wire, but i don't see a solid black wire, just the smaller black wires with a light blue stripe. any help would be appriciated. thanks.

 

Throw an OMH meter on it. Check them for continuity.

 

Putting an ohm meter on a potentially live wire is a great way to roach it. Never ohm out a live circuit.
What year and car are you working with. I can't find any Black/blue wires that should be nere there. Don't need to bother though. If the ground is the ONLY one you're having problems with, take the HU's ground right to the chassis. Find a good spot, clean it good, make good connection, go on with life.