I have your Factory Fit engine harness wiring, how do I hook up the wires to my starter motor? I have three posts, two small posts and one large post on my starter solenoid…

Typically, GM vehicles prior to 1982 have starter solenoids with three posts:

Post # 1: Battery – This is the large post on the solenoid which is usually found on the center top of the solenoid.  This is the post where the positive battery cable attaches along with any battery feed wires that the car might require.   These wires are usually heavy gauge red, or black wires and may contain a fusible link.

Post # 2: The “R” Post – this post is one of two small posts on the solenoid.   This post becomes hot only while the starter is cranking.  On an original points car, this post feeds a wire that sends full voltage to the coil during cranking.   This wire is know as the resistance bypass wire, as it bypasses the resistance circuit that will typically feed the coil when the car is running.  This is done to boost the coil output during engine start.   It is noteworthy that on some of our HEI conversion engine harnesses this wire is retained due to the design of the factory ignition switch and circuitry.   While factory HEI vehicles do not have this bypass wire, on some of our HEI conversion harnesses, this wire is still required and may be found on your harness.   This wire is typically yellow, but can be green, pink, or black with a pink or yellow stripe.  On typical GM starters this post is generally the small post closest to the engine block.   Occasionally you will see this post marked with a “C” instead of an “R.”

Post # 3: The “S” (solenoid) Post – this the other small post on the starter solenoid, and is typically the post farthest from the block.  This post will accept the purple wire on the engine harness.   The purple wire carries current from the ignition switch, often via the neutral safety switch, down to the starter to activate the starter.

Occasionally you will see a smaller gauge black wire leading down to the starter as well.  This will actually hook directly to small ground screw on the starter body itself.