Chevrolet said it well in his post on 11/24/03:
"a solenoid is nothing more than a wire wound around a piece of iron (core) to make an electromagnet...a magnet stays magnetic all the time...an electromagnet is magnetized only when electricity is applied...(look at those nice pictures mrmack posted...most of them show just two wires emerging...)
the earth is a big magnet with a north & south pole, because it has an (molten) iron core...many planetary bodies & sattelites are not, because they lack an iron core...
anyway, when one applies a current to the wire, it creates a magentic field...if one designs this device correctly, the iron core is either attracted or repelled, dependent upon the orientation of the poles...reverse to "polarity" of the wiring, that is, switch which wire is connected to positive & negative terminals of the baterry, and the magnetic orientation reverses, too...
so, the solenoid type electric door locks use this principal...push the conrol switch one way and the solenoid pulls the door lock linkage to "lock," push the switch the other way and it provides a reversed wiring connection so the solenoid "unlocks"...
solenoids are cool because they can operate things from a remote location, like your auto's door or trunk locks, or your home's doorbell chime...
in a vehicle with an electric key start, the key switch applies current to the engine's starter solenoid...this way, one doesn't have to step on the starter switch, like those of us with the foot starters...
with a relatively small amount of electrical energy (small wire), two things occur: 1) the solenoid pulls a linkage to engage the pinion gear of the starter motor to the ring gear on the flywheel and 2) connects the starter motor contacts to the battery (big cable) to start the cranking of the engine...
since nothing happens when you turn your key switch, your switch may not be supply any or enough power to the solenoid...to see if the solenoid/starter/battery cable part of the system is working, you can jump the solenoid terminal with the starter terminal (battery) to see if the solenoid engages and starter motor turns...if so, then you know to look for trouble back towards the keyswitch circuit...
hope this helps,
kepi"
