The purple wire, (purple arrow), goes to the smaller "S" terminal on the solenoid, (blue arrow). That is always the only wire that goes there. That is the one that activates the solenoid when it gets 12 volts from the starter relay, or in some cases, directly from the ignition switch.
The other small terminal "R", (yellow arrow), when used, is as a relay terminal. It gets 12 volts put on it during cranking, to bypass the ignition resistor for stronger spark and easier starting. That terminal is used on older cars and may not even exist on newer solenoids.
The red arrow is pointing to the generator's output wire. The red part of the wire is a spliced-in fuse link wire. It is slightly smaller in diameter so it's the weak link in the chain. Also, its insulation is designed to not melt or burn when the wire burns open. This wire goes directly back to the battery's positive post, but GM likes to use the larger stud on the solenoid, (orange arrow), as a convenient tie point since the battery cable also goes right back to the battery. No point in running two wires when they both go to the same place.
I suspect you're referring to the black wire by the green arrow. That is not shown as part of the starter circuit, but it is typically another circuit the uses the large terminal as a tie point, rather than running back to the battery. The arrow is pointing to a piece of heat-shrink tubing that covers a splice. That indicates it is the starting point for another piece of fuse link wire. This wire will feed multiple other circuits to potentially include exterior lights and horn, as well as the ignition / starter switch. With this wire broken off, you should find multiple systems, including the starter system, are dead.
This is a relatively simple repair, but you must be careful to never touch a metal tool to the large battery terminal, (orange arrow), and another metal part on the car, at the same time. That would create huge sparks and could weld the tool in place and cause it to become red-hot and melt. It is safer to disconnect the battery's negative cable, then continue with the repair.
Strip the end of the wire, then crimp on a new terminal, and bolt it onto the stud. You'll probably have to buy a small box of terminals from an auto parts store. The crimp end has to be small enough to crimp effectively around the wire, but the ring end has to be large enough in diameter to fit over the stud. That combination of sizes makes it an uncommon terminal that you may not find in a hardware store.
I prefer to solder the wire to the terminal after I crimp it. Due to the wet location, I pull the plastic cover off the crimp end, slide a piece of heat-shrink tubing onto the wire, crimp, then solder the terminal to the wire, then slide the tubing down and warm it to seal the connection. You can buy heat-shrink tubing with hot-melt glue inside. That will form a moisture-proof seal. The tubing and the glue strengthen the wire to reduce the chance of it breaking again.
You'll need to remove the large nut, then remove and discard the old terminal. Place the new terminal on the stud, then reinstall the nut.
Wednesday, April 19th, 2017 AT 2:27 PM