No dash lights, fuses and bulbs are good. Voltmeter indicates 12.2V on the circuit. Voltage drop on the ground side and there is still a voltage reading of 12.2V. What is wrong?

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A complete circuit needs a return path for current to flow. If the ground (return) side is open, the load can be energized on the hot side but no current can return to the battery, so the device won’t light even though the supply is present. In this case, the fuse and bulbs check out and a voltmeter reads about 12V on the circuit, which means the hot side is energised. The indication of a voltage drop on the ground side together with a still-present 12.2V reading points to a broken or poor ground path—the return path isn’t solid. The remedy is to inspect and repair the ground connection: check the instrument cluster ground and chassis ground points, clean corrosion, and ensure a secure connection back to a good ground. A quick confirmation is to temporarily connect the circuit to a known good ground and see if the dash lights come on. Other scenarios, like an open hot side or high resistance there, would not produce this same pattern of a solid 12V reading with no load current.