[goatless]

Originally Posted by ray_mcavoy

Yes, the 60 through 66 horn wiring is similar for all years. Although some of the early years had the color coding of the black & green wires switched around opposite of the later years. And many of the later years also had a power distribution buss bar built into the horn relay assembly.

The 20 W/OR/PPL (white/orange/purple, but pictured solid purple on that diagram) wire is a special resistance wire that takes the place of a ballast resistor. The use of a resistance wire (in place of a ballast resistor) was fairly common practice on many 60's & 70's GM vehicles.

Thanks for the clarification. My '64 has a ballast resistor. Apparently, it wasn't properly wired, as there's only one wire going to the + on the coil, and it comes from the ballast resistor. Guess that means it wasn't getting the full 12volt boost when starting.