The term stress in the machine, generally meaning the battery voltage. It is thus a constant voltage of about 12 V. The voltage depends on the battery charge and the outside temperature. It can be from 10 to 13 V. The generator creates a system voltage of about 14 V at medium speed.
The current intensity is indicated on the reverse side of the fuses and indicates the maximum current that can pass the fuse circuit without combustion and disengagement, thus chain.
The resistance depends on the following factors: cross-section, conductor material, consumer power, and so on.. For example, the resistance in the high voltage wires must not be too high: otherwise the spark at the spark plugs is not strong enough to ignite the air-fuel mixture and the engine will not start or operates intermittently.
For measurements in commercially available, so-called multi-purpose gauges. They combine in one instrument voltmeter, ammeter, and an ohmmeter.
For vehicles designed multi-purpose devices, through which can be measured by the engine speed, ignition timing and, in addition, voltage up to 20 V. When measuring the resistance of the device is usually limited to the area kiloomnoy 1-1000 ohms.
If you want to check only the presence of voltage (V), it is sufficient to use a test lamp. This applies only to circuits in which there are no electronic components, since they are extremely sensitive to high currents. Under certain conditions the units can even be disabled as a result of the connection of a control lamp.