G3GM 1973 to 1977 A-bodys. Chevelles, Monte Carlos, El Caminos, Laguna, 442, Cutlass, Malibu, GTO, LeMans, Century, Regal, Grand Am, Grand Prix, Sprint, Gran Sport, Can Am, Hurst-olds, and other 73-77 A-bodies
You guys with a 76 or 77 Chevelle or Monte on your fire wall just above the brake booster do you have a little breaker with a heavy maybe 1gauge wire going to it from inside the car? What is it? I think it is hot with the key on too. I can't find my wiring diagram right now and it's one of those things I forget about until I see it again.
Mine has that - 10ga with fused link. It supplies power to the HVAC relays (or did) allowing the fan to run on direct 12v when on high speed. Also supplied power to the mercury switched, under hood light.