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Measurement Equipment

Voltage measurement

The presence of voltage can be proved already with a simple light bulb or a control voltage indicator. However, in this case it is determined only if the voltage is applied at all. In order to determine the magnitude of the applied voltage, it is necessary to connect a voltmeter. First of all, by using a voltmeter to install the measuring range, which presumably is the measured voltage. As a rule, the tension in the car does not exceed 14 V. The exception is the ignition system: here the secondary voltage of the ignition system can reach up to 30 000 V. This high voltage can only be measured using a special measuring device - oscilloscope. First of all, by means of the selector switch is set range of DC voltage DCV, in contrast ACV-voltage alternating current. Then the selected measuring range. Since the vehicle is not in addition to the ignition system voltage above 14 volts, should be set the upper limit of the measuring range is slightly higher (15-20 C). If the measured voltage is obviously much lower, for example, it is a two volt range, it is possible to switch to a more narrow range, to achieve greater precision reference. If applied voltage higher than the specified measuring range of the device, the latter can be damaged.

In accordance with the figure, connect the wire meter parallel to the consumer. The red test lead is connected to the wires from the positive pole of the battery and the black test lead - a wire connecting the battery and the vehicle body, or directly to the vehicle, such as the engine block.

Example of control: if the engine does not run properly, because too slowly rotates the starter, it is advisable to check the battery voltage while pressing the starter. To do this, the red (+) wire of the voltmeter to the red terminal, connect the positive pole of the battery and the black wire - to the mass of the vehicle (-). Then instruct the assistant to press the starter and read the voltage. If the voltage is less than about 10 (at a temperature of the battery 20 ?� C), check the battery and possibly before the next attempt to start to charge it.

Current measurement

The car is relatively rare required to check the current. This requires an ammeter, which also is built into the combined meter.

Before measuring current meter is set to the range in which approximately is measured current. If this is not known, set the highest measuring range and if there is no indication in series switching devices on the lower ranges.

To measure current you must disconnect the electrical circuit and open circuit to connect the measuring instrument (ammeter). For this plug is pulled together, and the red (+) wire ammeter connected to a conductive wire. The black wire (-) is connected to the terminal that is connected to a broken line. In this case the ground contacts of the plug and the consumer to be connected by an auxiliary conductor.

In no case do not measure the strength of the current conventional ammeter to wire to the starter motor (150 A) or glow plugs for diesel engines (up to 60 A). Because of this occurring when high currents can burn meter. The garages for such measurements using an ammeter, equipped with pincers DC. This current clamp clamped isolated on the electric wire, and the current value is measured by induction.

Before measuring the resistance, you must be sure that the structural element connected to the ohmmeter is not energized. Therefore, each time pulling off the pre-plug, switch off the ignition, wire, for example, unplug the appliance or disconnect the battery. Otherwise, it may be damaged by the measuring device.

An ohmmeter connected to the two terminals of the user (load) or the two ends of the electric line. This does not matter which wire is connected to the meter terminals.

Measurement of resistance in the vehicle is divided into two main areas:

Check embedded in the electrical circuit of the resistor element or structure.

"Test passing current" in an electrical line, in the switch of the heating coil or heater. This check is not broken if the electrical circuit in the vehicle and therefore the connected electrical device can not function. To measure ohmmeter connected to both ends of the respective electric line. If the resistance is equal to O, then the electric current flows, ie. E. Electric line in order. In the case of the broken line indicates the meter infinity (in ohms).

Installation of additional electrical accessories

Wires when installing accessories should be laid to a set of wires mounted in the car, if possible, should always be laid along separate bundles with their mounting clamps and rubber grommets. In order to prevent the occurrence of noise while driving and avoid abrasion of wires again laid wires should be strengthened by means of adhesive tape, plastic mass, belt clips for attaching them, and so on. N. It is particularly necessary to pay attention to the fact that between the pipes a brake drive and rigidly laid wires have a minimum distance of 10 mm, as well as between the brake lines and wires that vibrate together with the engine and other parts of the vehicle, there was a minimum distance of 25 mm.

When drilling holes in the body then you need to clean up, otgruntovat and varnish the edges of holes. Inevitably formed in drilling swarf must be removed from the body.

In carrying out all the installation work, which relate to the electric wiring to prevent short circuits in the system, be sure to disconnect the earth wire of the battery (-) connecting it to the pole with the car body and hang it to the side.

If the battery terminals from the wires are disconnected, then under certain conditions, decommissioned storage device faults in the engine control system and transmission and anti-lock braking system and other electrical devices, such as radio and clock, and the accumulated value will be erased.