Understanding Electricity, the "Magic Fluid"
Electrical issues remain a problem for many, hardly suprising when we are
dealing with something totally invisible with no moving parts.
It helps to imagine electricity as water, the wires being the pipes that
conduct the water to where it is needed, in order to do the work.
The Battery is the water tank, the wires are the pipes, and the motorcycle
frame returns the water back to the tank to be used again.
So, lets work out something simple, like the motorcycle stop light.
Firstly, we need to conduct the water to the "tap" ,or faucet to our
american friends, that turns the water on and off. So, we need to have a
pipe from the tank...(battery) to the tap (stop light switch)... this is
coupled to the brake rod it allows the water through when the brakes are
applied. The pipe then meanders up to the stop light itself, where the work
is done, and after it goes through the bulb, the water returns to the tank
through the frame of the bike.
This is called a "circuit" for obvious reasons. If this circuit is broken
any where along its length, ie broken pipe, burned out bulb, faulty tap....
it will not work. Think of this problem as a broken or blocked pipe.
The motorcycle has many such circuits, each one independant of the other.
The indicator circuits are exactly the same, but in this case, an
"automatic" tap is used, on, off, on ,off ....
The ignition circuit is exactly the same, on, off, on, off.
The secret in fault finding an electrical problem involves just three
things.
1) Identify the actual problem
2) IGNORE all other circuits that are not related.
3) Follow the water through the faulty circuit until the fault is found.
Because the "water" is invisible, we need some way of detecting it easily. A
small test light can be constructed... nothing more than a small 12 volt
light bulb with a wire soldered to each terminal. One wire of the test light
is clipped to the motorcycle frame, the other can be "dabbed" on to
different parts of the circuit to see if there is water there or not.
Remember, ALL circuits are the same. Water must go in, and water must come
out.
The two important terms with electricity is voltage and current.
Voltage is equivalent to water pressure....or the height of the tank. A 12
volt tank is twice the height of a 6 volt tank.
Current is equivalent to rate of flow. This is the size of the pipe, and the
amount of water it can supply. Big flow, big pipe. Starter motor pipes need
to be larger than headlight pipes.
Lets use a fault finding example..... the headlight wont work.
We firstly connect our water detector.. (test light) one wire to the frame
of the bike.
The other lead is touched to the tank outlet (battery +) to see if we have
water.. (electricity). Yes, bulb lights. We then dismantle the headlight
bucket to gain access to the headlight bulb. We touch the water detector to
the headlight connections. No water.. test light remains dark. We then
check if the headlight tap .. (switch) is actually on. So, what have we
learned so far? The blockage is somewhere between the tank (battery) and the
headlight bulb. Looking at the wiring diagram, we find the coloured pipe
(wire) taking the water (electricity) to the headlight bulb is red. We then
visually follow the red wire from the battery to the switch, and from the
switch to the headlight bulb, looking for bad connections/broken wires. Do
the easy and obvious first. If all looks fine, we can safely assume we have
a faulty headlight switch as all other possibilities have been checked.
Before dismantling the switch, we could temporarily complete the circuit by
"bridging" the headlight bulb direct to the battery thus bypassing the
suspect switch, double checking your diagnosis. If the headlight then works,
you have isolated the problem, and all that remains is the repair.