To the ignition and starter we go...

Well we discussed the battery last time as the source of stored power
in your automobile.  Now what happens when you need it - for example, to
start the car.  You push the button on key fob to unlock the car and
expect it to unlock the door. Well it worked and the door lock solenoid
pulled the door lock in the direction to unlock the door. Your in the
car and you put the key into the ignition switch and turn it to the
start position.  Now what happens next? Behind the  key is a switch
that when turned supply electrical energy to the starter solenoid.  It
takes a lot of electrical energy to turn the engine over.  A lot more
energy then can be supplied by the key switch. So the key switch
supplies a small amount of currant to a solenoid
on top of the starter.  I just realized that I have been using the word
solenoid many times without explaining what it is and does.  It is a
electrical device that when electrical current is supplied to it,  a
electro magnetic field is generated within its windings and pulls a
solid metal object to it. This movement may push or pull a rod or lever
to make a mechanical action.  In the case of the door lock it usually
does this.  In the case of the starter it pulls a lever which engages
the starter gear into the fly wheel teeth and at the same time closes a
very strong electrical switch to apply a large amount of electrical
currant to the starter motor. This is what happens when the key is
turned on the modern auto. In the old days, before this system was
invented, a pedal or a starter button on the floorboard of the auto was
used to engage the starter and make this electrical connection.
    Well back to today, some autos have started using a button on the dash
to start the engine after the computer has identified you as the
regular driver for that auto through a key fob in your pocket.  Driver
identification can go as far as adjusting the drivers seat, mirrors and
pedal cluster for each driver that uses the auto. I have not had to
work on one of these autos yet and I am not looking forward to that day. Now when
turning the key to energize the starter motor to engage the flywheel
that is bolted to crankshaft it starts to turn.  The
crankshaft must turn greater then 400 revolutions per minute (RPM's)
for the fuel pump to be signaled to start pumping fuel to the injection
system.  The reason this threshold must be met is in case of the key is
left on, the fuel pump would not be running with out the engine
running. Also in case of a severed fuel line due to a accident or major
fuel leak.  As the crankshaft turns, a crankshaft sensor tells the
ignition system to supply spark to the spark plugs and supply fuel to
the combustion chamber by opening and closing the fuel injectors at the
appropriate time.
    I also just realized that keys have also come a long way.  Many new
auto have a chip embedded in the key so as to identify it to the auto
security system.  There is on problem when the chip is erased or altered by some electrical source in your
pocket or purse.  If the damaged key is inserted into into the ignition
switch the antitheft system locks out and
auto must be towed to the dealer for reprograming before even a spare
key can start it.  I think I have exhausted the key and starter
explanation.  Next time I will poke my head back
under the hood in the garage for more under the hood inspection.