On some cars the front lighting harness provides power to the voltmeter. If you wish to be correct then get the right harness. If you just want it to work then you can run wires anyway you like. Just use the correct guage and overload protection.
A forum community dedicated to Chevrolet Chevelle owners and enthusiasts. Come join the discussion about restorations, builds, performance, modifications, classifieds, troubleshooting, maintenance, and more!