nothing to do with a mustang but please help

1991ish dodge aries car, panasonic head unit
there is a wiring harness connected to a panasonic head unit; out of the harness comes red & yellow for power, but no black for ground to match to the black on the head unit. coming from the car wiring there was a black with white line going to a blank slot on the wiring harness, so i moved the dimmer wire from its slot in the wiring harness over to the correct slot to use it as the ground. wired it up, cd player went on, everything was great...til i found the dash lights didnt work. so i unplug the cd player harness clip, still no dash lights. i connect the orange dimmer wire in the wiring harness (now back in its original slot) to the red 12v power source, dash lights go on; but they stay on until the key is removed even with the headlights turned out. after fiddling with some more wires ive found no combination that will allow the dash lights to get power again and the cd player to work, im totally stumped...please help

iskwezm said:

dont worry about the dimmer wire, just make a new ground

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i can do that, ground it to bare metal somewhere else...but the dash lights wont come on unless i touch a power source to them now, at which point they stay on until the key is removed regardless of wheter the headlights are on.