Electrical schematic/ladder diagram question

[jonbot]

Looking at the wiring/ladder diagram for my '79 SC, I'm trying to figure out why it looks like the starter solenoid has two coils in it, anyone have any idea?

Here's the part of the diagram I'm talking about circled in red:

[1982911SCTarga]

As a follow-up question, when looking at a wiring diagram such as the one posted, are the numbers midway along a wiring run a metric reference to the gauge (thickness) of the wire used? The references, for example, can be 0,5; 1,5; and 2,5. Confirming this would be helpful in tracing a wire that has a different color than spec'd in the diagram.

Thanks!

Brian

[HawgRyder]

OK....as per diagram
The top wire coming in is the Hot wire from the battery...the left side of the coil is the activation (pull in) of the coil and the right side is the contacter for the power to the starter.
The wire coming out of the bottom of the coil goes to ground.
Obviously when the key is turned...it sends power to the coil (pull in) and activates the main power to the starter.
Did I do good?...LOL
Bob

[jonbot]

Bob, one of the leads coming out of the "bottom" of the coil runs to ground, that's understandable. The other one intersects the wire that runs over to the CSV circuit, that's the part I don't get. There must be something I'm not understanding

[Brad01mc]

I think the answer is that you don't want the rear defrost to be on while you crank the starter, so I think the solenoid is acting like a 2 pole switch. If the key is in the ignition position, the rear defrost will be on, but if you try to start the car, the electricity is removed from the rear defrost circuit.

This is my guess if F & N are the rear defrost wires (F) and fan (N).

Brad

[911pcars]

Originally Posted by jonbot

Bob, one of the leads coming out of the "bottom" of the coil runs to ground, that's understandable. The other one intersects the wire that runs over to the CSV circuit, that's the part I don't get. There must be something I'm not understanding

Allow me to make a guestimate.

Once the engine starts, the driver releases the ignition switch to de-energize the starter solenoid. This eliminates source voltage from the top of the coil and should open the power circuit to the motor. However, residual magnetism could remain and keep the solenoid energized. To encourage the solenoid coil to open the contacts in the power circuit, there's a current path from starter to coil, but in the opposite direction. This reverses the polarity of the magnetic field to encourage the power circuit contacts to open (if closed).

Sherwood