Mid 70's: Neighbor's Olds…
Mid 70's: Neighbor's Olds had taillights out. Bulbs okay. I took it to my mechanic friend, who took a long jumper wire from brake switch to the bulb. Working!
He found that a couple feet from either end of the circuit, GM had inserted aluminum wires to save money. This was about the time people's houses caught fire from aluminum/copper workbox connections corroding. New wires solved the problem, but many of these old cars still have no brake lights.
He also solved a Honda Accord with intermittent electrical problems caused by a wiring harness caught under the floor fusebox. Honda never found it in many trips by the owner.