[VetteVet]

This diagram shows it pretty clearly. The red arrows point out the brown/white resistance wire that originates at the key switch joined with the brown acc wire to the fuse panel for panel power. The brown/white 24 gauge wire runs to the inside of the firewall block where it joins an 18 gauge brown wire from the gauge cluster from the alternator charging light. Each of these wires provides 10 ohms of resistance to the alternator regulator to excite the alternator fields. Thus you can see why the alternator will charge without the gauge cluster being plugged in provided that you plug the brown wire into the alternator. This diagram shows the wire that plugs into the alternator as a brown/white 18 gauge wire yet it only says brown at the bulkhead.