What do the two small wires do. Obviously I know that one energizes the solenoid, but I was trying to test them with a volt meter and didn't have any help, so couldn't turn key to start position. Mechanic friend told me that yellow goes to inside small lug on solenoid, which is marked S, and black goes to outer one. When I hooked it up this way the starter wouldn't activate. I'd like to understand the system better.

The R terminal feeds a full 12 volts to the coil during cranking, it is ONLY powered during cranking. Typically the coil gets less than 12v due to the resistor wire or ballast resistor. I'm talking about the stock stuff, pre-HEI.

All of the Chevys that I have worked on over the years used a purple wire going to the "S" terminal on the starter solenoid.

All of the Chevys that I have worked on over the years used a purple wire going to the "S" terminal on the starter solenoid.

That's what I was thinkin', but the only two to the solenoid area are yellow and black. I don't see signs of an obvious splice back up in the harness, but don't want to split tape to see for sure. Ended up with yellow on R and black on S terminals, and it cranks now.:confused: Reversed it wouldn't do anything, although it would run when cranked with a remote starter switch hooked up.

Thanks for the help guys.:thumbsup:

That's what I was thinkin', but the only two to the solenoid area are yellow and black. IThanks for the help guys.:thumbsup:

The purple wire's probably been toasted to black after all these years.;)
BillL

Yellow wire goes to 'R' terminal on starter, other end goes to + on ignition coil if you still have points ignition. Not needed with HEI ignition. 'S' terminal should be purple from neutral safety switch and back to ignition switch.

Much like the purple "S" wire the yellow wire feeds full battery voltage to the + side of the coil ONLY during cranking. As soon as you release the ignition key the + coil voltage reverts to the voltage coming thru the ballast resistor wire coming from the ignition switch.