The harness that feeds the rear lights might be the culprit. It runs along the driver's side of the floor in the cabin, through the rear bulkhead by the driver's rear wheel and back into the trunk. There is a good possibility that the wires in this harness are made of aluminum. I found this out in my Monte. When new and shiny and well insulated, the aluminum harness will work well. Age and oxidation at the terminal ends and breaks in the wire that go unfound can cripple it. These wires are not stranded like their copper counterparts, they are usually just one heavy wire. What may have happened is that the wire that feeds the brake lights has either corroded or broken in the connection housing that is attached to the trunk pan near the driver's side tail light assembly. It could be a broken ground lead terminal or attaching bolt as mentioned, or it could be the power lead to that group of lights. Aluminum wires are not easy to fix. Normal solder does not work with them and they are very sensitive to heat where copper is more tolerant. The wire itself has to be sterile clean; any contamination will ruin the connection and cause problems. This harness is an issue that I will be having to deal with some time in the immediate future myself as I have to run a circuit check on my back up lights due to swapping in a four speed. this summer past.
Nick
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