No ground "wire" for the dash cluster in the traditional sense (copper strands with insulation). The dash cluster ground is a actual metal wire with a loop on the free end that is bolted to the back of the circuit board. That metal wire comes forward across the top of the cluster and is supposed to loop around the center of the 5 black oxide Phillips head screws that mount the plastic dash bezel face (the plastic face the instrument cluster attaches to) to the metal dashboard.

Many of us have had reason not to trust that factory ground and have run a separate regular insulated wire from a ground bolt on the back of the instrument cluster to a good ground point on the metal dash.