Blue single wire. It is covered by some shrink tubing, but at the end, you can see some blue. Most of the time I see it put on the ground by mistake in the center bottom of the radio. Remove it and put it at the top left corner.

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Benzmac:
Donnie Drummonds
1991 GMC Syclone
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
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