Hi, I was taking out my old cd player and radio pod out of my 86 trans am and noticed a loose wire. It was a brown wire that was NOT part of the radio wiring harness. It was coming from under the dash I think. It had this black plastic box with connections on it and it said "PACK-CON II" What is this used for? Thanks.

 

I have that same wire.

It's also brown.

It's loose.

 

Not sure about the black box thing, but the extra wire is commonly the illumination wire for the OEM radio. Tape if off. If you don't it can short out when the lights are one and toast the tail lights/dash lights(seen that way to many times in GM cars). My cousin actually used that for a ground wire--the radio would work fine, until the lights turned on .