Posted by Sherman in Idaho [24.32.202.166] on Sunday, March 17, 2013 at 15:18:34 :
In Reply to: photo of solenoid posted by Sterling [99.98.76.231] on Sunday, March 17, 2013 at 13:35:23 :
Makes perfect sense now. You have a Ford starter relay. Normally when someone calls it a "solenoid", they're referring to the smaller cylinder that's part of the starter motor and that when energized works a lever to engage the pinion gear and also closes the contacts to connect the battery to the motor.
On the Ford relay, one heavy terminal goes to the battery and one to the starter, as you probably surmised, but you have to hook the cables to the CORRECT heavy terminals. They are not interchangeable. Then, of the two small terminals, ONE of them energizes the relay. The other is a separate contact on the relay that gets connected to the battery ONLY when the relay is energized. Electrically, it's connected to the battery at the same time as the starter motor is (while cranking). That light terminal goes straight to the spark coil to bypass the ballast resistor while cranking. I don't recall off hand how each of them is marked, but they're marked somehow. If you mis-wire the heavy terminals, but hook your starter switch to the correct small terminal, the relay will pull in and the engine will crank, but the ignition circuit will be screwed up. You might wonder why they need a separate terminal to bypass the ballast resistor, since it gets connected to the battery at the same time (when cranking) as the main starter motor terminal is, so you'd think they could just run a wire from the heavy terminal to the coil. The reason that won't work is that although it would start the engine just fine, as soon as you let off on the starter switch, the starter motor would ground out the spark coil and the engine would stop. I have to wonder if the Vintage Wiring harness was even designed to work with a detached Ford-style starter relay. It can obviously be made to work, but the instructions that came with it might not be right for this non-standard application.
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