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Disciplines
Switch off the ignition prior to making any connection or disconnection in the system.
An electrical surge can be caused by disconnecting 'live' connections which can damage
electronic components.
Ensure hands and work surfaces are clean and free of grease, swarf, etc. as grease
collects dirt which can cause tracking or high- resistance contacts.
Prior to commencing any test, and periodically during any test, touch a good earth to
discharge body static. This is because some electronic components are vulnerable to
static electricity.
Electrical Wires
All the electrical wires are either single-colour or two-colour and, with only a few
exceptions, must be connected to wires of the same colour. On any of the two-colour
wires there is a greater amount of one colour and a lesser amount of a second colour. A
two-colour wire is identified by first the primary colour and then the secondary colour.
For example, a yellow wire with thin red stripes is referred to as a 'yellow/red' wire; it
would be a 'red/yellow' wire if the colours were reversed to make red the main colour.
Electrical Testing
For any electrical system to work, electricity must be able to flow in a complete circuit
from the power source (the battery) via the components and back to the battery. No
circuit means no electrical flow. Once the power has left the positive side of the battery
and run through the component it must then return to the battery on its negative side
(this is called earth or ground). To save on wiring, connections and space, the negative
side of the battery is connected directly to the frame or engine. Around the frame and
engine will be various other ground points to which the wiring coming from components
will be connected. In the case of the starter motor it bolts directly to the engine, which is
bolted to the frame. Therefore the frame and engine also form part of the earth return
path.
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