2000 4Runner light bad ground

For those who wonder about voltage drop problems I had a good one. My 2000 4Runner overhead map light stop working. I checked the lamps-good resistance. Took lamps out and checked power at the connectors-good power 12v; however, when I put the lamps back in and put a load on that circuit, the power would drop to 0 volts. I dropped the unit down to check resistance of the wires- good 000 ohms. Something was stealing the volts from the lamps. I next checked the ground connection point, which showed surface corrosion under the bolt-found the thief. Cleaned it up and it works fine now. :cheer: