Renault Training Electricity LEV1

ELECTRICITY (level 1)

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CONTENTSThe basics of electricity 4

General formulae and circuit types 12Measurement of electrical quantities 20Inspecting and charging the battery 24

Procedures to be followed on disconnection of the battery 31Checking the ignition circuit 35Checking the charging circuit 39Connections and harnesses 43

Trouble shooting and repairing an electrical circuit 46Questionnaire 51

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THE BASICS OFELECTRICITY

The electric current 5Electrical energy 6

The simple electric circuit 7Electrical units of measurement 8

Protection of circuits 11

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The basics of electricity

The electric currentElectricity is part of our everyday lives. It is used in vehicles where it actuates thefollowing operations:- supplying electrical systems.- circulation of information in the form of signals.

Definition of the electric current

Matter contains positive charges, protons, and negative charges, electrons. Nor-mally there is an equal number of electrons and protons: the matter is neutral; itdoes not have an electrical charge.

The movement of electrons creates an electric current.

Direction of the electric current

It is conventionally said that the current flows from the positive terminal to thenegative terminal.

Direction of the current

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Electrical energyElectricity is a form of energy.

Production of electrical energy

To produce an electric current, another source of energy is required, for example:- a battery transforms chemical energy into electrical energy.- an alternator transforms mechanical energy into electrical energy.

Producers of electrical energy

Consumption of electrical energy

The electricity produced may be transformed into another form of energy, for ex-ample:- a bulb transforms electrical energy into light energy.- an electric motor transforms electrical energy into mechanical energy.

Consumers of electrical energy

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The simple electric circuitComposition of a simple electrical circuit

A simple electrical circuit is a loop containing a source of electric current and aconsumer, linked by conductive wires.

Simple electrical circuit

Circulation of current in an electrical circuit

An electrical circuit must be closed to enable the current to circulate from thesource to the consumer and return to the source.

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Bodywork as earth

In a vehicle the bodywork is commonly used for the return of the current. This isknown as the bodywork earth.

Bodywork as conductor

Electrical units of measurementThree units of measurement define the properties of the various elements of anelectrical circuit:

• voltage

• resistance

• current

A multimeter is used to measure these units of measurement.

Voltage

Voltage is defined as the difference in potential between two points of a circuit.

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Voltage

Voltage is a unit of electricity symbolised by the letter U.The unit of measurement of voltage is the volt , symbolised by the letter V.

resistance

Resistance is the opposition to the circulation of current in an electrical circuit.

Resistance

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Resistance is a unit of electricity symbolised by the letter R.The unit of measurement of resistance is the ohm, symbolised by the Greek letterΩ (omega).

A material which poses little resistance to the circulation of the current is a con-ductor. Conversely, a material which poses high resistance to the circulation of thecurrent is an insulator.

Current

The current is the amount of current which crosses a point in the circuit at a givenmoment.

Current

Current is a unit of electricity symbolised by the letter I.The unit of measurement of current is the ampere, symbolised by the letter A.

Protection of circuitsConcept of short-circuit

When the initial path of the current is deflected in a circuit with resistance practicallyzero, the term short-circuit is used.

Use of fuses

Fuses protect current circuits from excessive current.

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When a fuse blows, it is essential to identify the cause of excessive current andrectify it. The size of the replacement fuse should be similar to the original one.

Use of fuses

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GENERAL FORMULAEAND CIRCUIT TYPES

Ohm’s Law 13Series and parallel circuits 14

Electrical power 15The concepts of electromagnetism 16

The electric motor 18

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General formulae and circuit types

Ohm’s LawDefinition

Ohm’s law is one of the fundamental laws of electricity. It combines in a formulathe units of measurement we have seen above. The voltage U is equal to theresistance R multiplied by the current I.

This law is represented by the formula: U = R x I.

Ohm’s Law

At constant voltage, when the resistance is increased, the current is reduced. Con-versely, when the resistance is reduced, the current is increased.

Examples of the use of Ohm’s law

Calculate the resistance of an element with current of 2 A passing through, with avoltage at the terminals of 12 V.Result: given that the resistance R is equal to the voltage U divided by the currentI, the resistance is 6 Ω (12 V ÷ 2 A).

Concept of potential difference

The potential difference is the voltage drop determined in a conductor of substan-tial length.

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Series and parallel circuitsIn electricity, there are two main types of circuit: series circuits and parallelcircuits.

Series circuit

• The current has a single route and passes through the components one afterthe other.

• The current is the same at all points of the circuit.

• The total voltage at the terminals of all the consumers is equal to the sum ofthe voltages at the terminals of each consumer.

• The total equivalent resistance is equal to the total of the individual resistancevalues.

Series circuit

Parallel circuit

• The current divides to pass through the components located in the variousbranches.

• The voltage is the same in all the branches.

• The total current is the sum of the currents passing through all of the branches.

• The total equivalent resistance is less than the smallest of the individual resis-tance values.

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Parallel circuit

Electrical powerDefinition

Power corresponds to the quantity of energy which a component absorbs for itsoperation.

In an electrical circuit, the electrical power P is equal to the voltage Umultiplied bythe current I (P = U x I).

Electrical power

Power is a physical unit symbolised by the letter P.The unit of measurement of power is the watt, symbolised by the letter W.

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Example of calculation of power

Calculate the power of an electric motor with a current of 100 A flowing through,with a voltage at the terminals of 12 V.Result: given that the power P is equal to the voltage U multiplied by the currentI, the resistance is 1200 W (12 V x 100 A).

The concepts of electromagnetismMagnetism

A magnet is a body with magnetic properties, that it, it has the capacity to attractferric metals. It has two poles at its extremities: a north pole and a south pole.Around these poles is a space where a force of attraction known as the "magneticfield" is exercised.

If the identical poles (S/S or N/N) of two magnets are brought together, they repelone another. Conversely if the opposite poles (N/S) are brought together, theyattract one another.

Electromagnetism

Electricity and magnetism are two linked phenomena. In fact, the circulation ofan electric current in a conducting wire wound round a core of soft iron enablesa magnet to be obtained. If the current is cut off, the magnetic field disappears.Such a magnet is called an "electromagnet”.

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Electromagnetism

Electromagnetic induction

Placing a magnet in close proximity to a conducting wire generates a current inthis conducting wire. This phenomenon is called "electromagnetic induction”.

Electromagnetic induction

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Application of electromagnetism: the relay

The relay is an application of electromagnetism. It consists of a coil fed by a com-mand circuit and a contactor kept open by a spring. When the command circuitbreaker is closed, the circuit flows round the coil. The coil becomes an electro-magnet and attracts the contactor to close it.

Application of the relay

Thanks to a low-intensity current in the relay coil, the circulation of a strong-inten-sity current can be controlled in the power circuit. In a vehicle, the relay enablesthe length of the thicker wires to be reduced and a lower intensity of current to beused in the circuit-breakers and the wiring.

The electric motorThe electric motor is another application of electromagnetism.

The motor converts the electrical energy into mechanical energy.

In a vehicle, the electric motors are fed by a continuous current (e.g.: the windowcontrol motor, the starter motor and the fan motors).

Composition of an electric motor

Simplified, an electric motor is principally made up of an electromagnet mountedon a spindle between the two poles (south and north) of a permanent magnet.Each extremity of the electromagnet is connected to a segment of the armaturecommutator mounted on the shaft. The segments of the armature commuta-tor are insulated from both the shaft and each other. When the shaft turns, thesegments come into contact with the electricity supply by means of brushes.The

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interactions between the magnetic fields of the electromagnet and the permanentmagnet create and maintain the movement transmitted to the motor shaft.

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1) Electromagnet2) Permanent magnet3) Armature commutator4) Brush

In a real motor there are several coils and feed segments.

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MEASUREMENTOF ELECTRICALQUANTITIES

Multimeter 21Measurement of electrical quantities 23

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Measurement of electrical quantities

MultimeterMost electrical measurements can be carried out using a multimeter.

Description of the multimeter

A multimeter generally has the following elements:- a display screen- a selection switch- three or more connection terminals- two test leads of different colours, black and red

Multimeter

The selection switch enables the function of the multimeter to be defined accord-ing to the amount of electricity to be measured. This selection should be madebefore each measurement. It is enough to position the switch opposite the symbolwhich corresponds to the unit of measurement.

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The connection terminal denoted by the letters COM for “common” is exclusivelyreserved for the connection of the black lead. The other terminals marked withthe symbols of the units of measurement are reserved for the connection of thered lead and used depending on the measurement to be carried out. The end ofeach lead is fitted with a touch point to ensure the contact with the element to bemeasured.

The multimeter screen shows the value measured. A bar graph gives anoverview of the variations in this value over a period of time.

Measurement of electrical quantitiesMeasurement of voltage

- Set the multimeter to voltmeter position.- Connect the red lead to the corresponding terminal of the multimeter and theblack lead to the COM terminal.- Position the red touch point of the multimeter on the positive terminal and theblack on the negative terminal.

Measurement of current

- Set the multimeter to ammeter position.- Switch off the current from the circuit.- Connect the red lead to the protected terminal marked 10 A and the black leadto the COM terminal.- Insert the multimeter in series in the circuit.- Switch the current to the circuit back on.

The multimeter enables low-intensity currents to be measured. It is not designedto handle more than 10 A.

For currents in excess of 10 A, a clamp-on probe is used, which is placed aroundthe cable on which the measurement is to be taken.

Measurement of resistance

- Set the multimeter to ohmmeter position.- Switch off the current from the circuit.- Remove or isolate the component from the circuit.

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- Connect the red lead to the corresponding terminal of the multimeter and theblack lead to the COM terminal.- Place the touch points on the terminals of the component.

IMPORTANT

When measuring the resistance, as the ohmmeter generates a current, itis strictly forbidden to measure the resistance of pyrotechnic elements ofairbags and seatbelt pretensioners. Such a current may trigger the firingof the airbag modules.

CLIP in multimeters

CLIP, equipped with a physical measuring unit, also enables the voltage, currentand resistance to be measured.

CLIP

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INSPECTING ANDCHARGING THE

BATTERYComposition and functioning of the battery 25

Safety instructions 26Visual inspection of the battery compartment 27Checking the battery with measuring tools 28

Battery charge 29

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Inspecting and charging the battery

Composition and functioning of the batteryThe role of the battery is to store energy in chemical form and release it in the formof electricity.

Battery

The battery has the form of a box with two terminals: one positive, the other neg-ative. The polypropylene container is divided into six compartments. Each com-partment of the battery contains an element made up of a stack of positive platesconnected to the positive terminal and negative plates connected to the negativeterminal. All these plates are immersed in a conductive fluid called the electrolyte,which is a mix of water and acid.

The production of electrical energy is the result of chemical reactions between thevarious elements of the battery.

Safety instructionsThe sulphuric acid used in batteries is a dangerous substance. Before handlinga battery, gloves and safety goggles must be worn. In case of contact of the acidwith the skin or the eyes, rinse with plenty of clean water and consult a doctor.

Due to the presence of active substances, it is strongly recommended that sourcesof heat (cigarettes, welding, etc.) are avoided, as these present an explosion risk.

To prevent short circuits, do not place metallic objects on the battery.

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Before connecting or disconnecting the battery, disconnect all consumers on thevehicle.

Battery label

A label shows the principal electrical properties of the battery. Three values aregenerally shown, for example 12 V ∼ 65 Ah ∼ 720 A :- “12 V” is the nominal voltage of the battery in volts,- “65 Ah” indicates the capacity of the battery in ampere hours.- “720 A” is the maximum current in amperes which the battery can deliver at lowtemperature.

Battery label

Corrosion of the battery

Corrosion of a battery is usually the result of poor maintenance (acid completelyused up, battery without charge for a prolonged period, etc.).

Corroded battery

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Leakage currents

Leakage currents are considered normal if they do not exceed a few tens of mA.On recent vehicles there is often a delay time before power supply commences. Itis therefore necessary to wait a few seconds after cutting the contact and closingthe doors before measuring leakage currents.

The best tool for this measurement is the multimeter. A clamp-on probe does notmeasure precisely currents less than 1 A. Measurement is made directly at thebattery or at the location of the consumer cut-out fuse.

Visual inspection of the battery compartmentBefore checking the battery with a measuring tool, it is necessary to check thefollowing points:

• the absence of cracks or breakages of the casing and the cover

• the condition of the terminals

• the tightness and correctness of the electrical connections

• the electrolyte level (depending on the model of the battery). In general there isa mark to indicate the level. If not, the level should be 20 mm below the plates.

Battery compartment

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Checking the battery with measuring tools

Midtronics

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The Midtronics enables thebattery to be checked withoutdisconnecting it. The level ofcharge is indicated in clear onthe screen. The main advantageof the Midtronics is its ease ofuse.

Multimeter

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The multimeter not only enables thevoltage of the battery to be mea-sured, but also the majority of elec-trical checks to be made.

CLIP

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CLIP, equipped with its physi-cal measuring unit, also enableselectrical checks to be made.

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Battery chargeThe chargers

Two battery chargers are approved by the Methods department: OPTELEC andBOSCH.

Battery charger

Safety instructions for charging the battery

- The area should be well ventilated as the combination of gases produced duringcharging is explosive.- It is forbidden to charge several batteries in series.- Several batteries may be charged in parallel in exceptional cases.

Important: to disconnect the battery from the vehicle, it is recommended that thebattery earth terminal is first disconnected.

Connecting the charger to the battery

- Disconnect and remove the battery from the vehicle.- Connect the positive terminal of the charger to the positive terminal of the battery(red lead).- Connect the negative terminal of the charger to the negative terminal of the bat-tery (black lead).

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Charging properties

Charging speed

• Slow charging is carried out using a weak current, generally between 1/20thand 1/40th of the capacity of the battery. This method is useful for batteries invery poor condition (battery discharged for several weeks).

• Normal charging is carried out using current of 1/10th of the nominal capacity ofthe battery. A complete recharge lasts several hours.

• Rapid charge enables batteries with around 80% charge to be safelyrecharged.

Important: if charging continues when the battery is charged, it will cause effer-vescence in the battery compartments. This presents a risk of explosion.

Charging efficiency

The charging efficiency of a battery is around 80%. This value means that a batterywhich has absorbed 100 Ah will only retain around 80 Ah. A 40 Ah battery willabsorb around 50 Ah to charge fully. A full charge takes between 4 and 10 hoursfrom the initial charging of the battery.

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PROCEDURES TOBE FOLLOWED ONDISCONNECTION OF

THE BATTERYRepairs 32

Possible consequences of disconnecting the battery 34Procedures to be followed following disconnection of the battery 34

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Procedures to be followed on disconnection of the battery

RepairsTo repair a vehicle whose battery is discharged or inoperable, an external batteryis used with jump leads or an auxiliary starter. This enables the vehicle’s engineto be started.

External battery and jump leads

- Use electrical jump leads in good condition of sufficient size.- The two batteries should have an identical nominal voltage (12 V).- The capacity of the battery supplying the current should be at least equal to thatof the discharged battery.- A battery which is frozen up should be thawed before charging.

Jump leads

Follow the order of connection of the cables: positive of the faulty battery thenpositive of the service device, earth of the service device, then earth of the faultybattery.

Auxiliary starter

The auxiliary starter is a portable device comprising an internal 12 V battery.

It enables all vehicles with a discharged battery to be started while safeguardingthe memories of electronic features saved during the works on the electrical cir-cuits.

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The unit is connected to the mains or the cigarette lighter socket to recharge itsinternal battery. A screen or LED displays indicate the charge levels.

Auxiliary starter

Possible consequences of disconnecting the batteryWhen a battery is disconnected to be replaced, the consequences do not generallylead to immobilisation. We will show you these consequences and the proceduresto be followed following disconnection of a battery.

Consequences

- the clock is no longer set.- the car radio code needs to be coded.- the pulsed operation of the window winders is inactive.- the pulsed operation of the sunroof control is inactive.

Disconnection of the battery does not interfere with the following elements:- memory of the driver’s seat settings (seats, rear-view mirrors, air conditioningsettings)- the headlight settings

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Procedures to be followed following disconnectionof the batteryThe procedures to be followed following disconnection of the battery are describedin the Technical Documentation:- Repair Manual (in particular Section 8);- Technical Notes- User Instructions for the vehicle.

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CHECKING THEIGNITION CIRCUIT

The ignition circuit 36Preliminary checks. 37

Checks using measuring tools 38

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Checking the ignition circuit

The ignition circuitThe main components of the ignition circuit are as follows:- the battery- the starter motor- the toothed ring gear- the ignition switch- the electrical connection cables

The batteryhas already been described.

The starter motor comprises three separ7ate parts, as follows:- the solenoid, which moves the starter by means of the fork and at the same timecompletes the electrical power circuit to supply the starter motor.- the DC electric motor which starts the engine.- the fork and starter unit, which provides the connection between the starter motorand the toothed ring gear of the flywheel.

Section of a starter motor1

2

3

4

1. Solenoid

2. Motor

3. Fork

4. Starter

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The toothed ring gear is located on the flywheel of the engine. It transmits thetorque of the starter motor to the engine

The ignition switch provides remote control of the starter motor solenoid (directlyor through a relay or the interconnecting unit).

The electrical connection cables form two distinct power circuits:1. the power circuit which transmits the current from the battery to the starter motor.2. the control circuit which transmits the control current to the solenoid duringignition.

Preliminary checks.Visual checks.

First perform a visual inspection (traces of fluid, connection of the cables, conditionand completeness of the various elements of the ignition circuit).

Audible checks.

The most common problems discovered on actuating the starter motor:

- There is no sound at all: this indicates that the solenoid has not been actuated.Investigations should concentrate on the power source to the solenoid, the condi-tion of the solenoid coils or the brushes of the starter motor. The possible effectof outside elements (immobiliser device, automatic transmission left in gear, etc.)should not be disregarded.

- There is an intermittent metallic noise but neither the electric starter motor northe vehicle’s engine appear to turn: this may indicate a problem with one of thecoils of the solenoid or the power supply to the electric starter motor.

- The starter motor turns but not the engine: there is a meshing problem (fork,starter).

- The engine turns over but does not start: in-depth tests must be carried out onthe starter circuit. Other systems within the vehicle may be the cause (immobilisersystem, automatic transmission etc.).

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Checks using measuring toolsChecking the power supply and earth

It is also necessary to check the power supply and earthing of the starter motorcircuit. This check may reveal problems with the electrical connections.

Inspection points of the charging and starter circuits

Checking the current consumed

The current consumed during the actuation of the starter motor varies between 100A (low-CC petrol engine) and 250 A (high-CC diesel engine). This value shouldbe recorded using a clamp-on probe.

If the current is very low, this could indicate a starter motor problem, a low batteryor faulty electrical connections.

If the current is very high, this could indicate a short circuit at the starter motor ora mechanical element, which is blocking the starter motor.

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CHECKING THECHARGING CIRCUIT

The charging circuit 40Preliminary check of the charging circuit 41

Checks using measuring tools 41

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Checking the charging circuit

The charging circuitThe main components of the charging circuit are as follows:- the battery- the alternator- the voltage control system- the alternator drive belt

The battery has already been described.

The alternator is a rotating electrical machine driven by the vehicle engine bymeans of a belt. Its function is to transform mechanical energy into electrical en-ergy to power the electrical consumers and maintain the charge level of the battery.

Alternator

The voltage regulator, an integral part of the alternator, adapts the output of thealternator to the requirements of the battery and the vehicle. When the voltagefrom the alternator is too low, the regulator increases the energising current in thecoils of the stator. When the output voltage is too high, the regulator reduces theenergising current in the coils of the stator.

The drive belt transfers the mechanical energy from the engine to the alternator.The condition and the tension of the drive belt must be checked in accordance withthe manufacturer’s recommendations.

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Drive belt

Preliminary check of the charging circuitFirst perform a preliminary visual inspection (connection of the cables, conditionand completeness of the various elements of the charging circuit).

Checks using measuring toolsChecking the power supply and earth

It is also necessary to check the power supply and earthing of the charging circuit.This check may reveal problems with the electrical connections (poor connections,corrosion).

Inspection points of the charging and starter circuits

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Measurement of current intensity

The current produced by the alternator should be greater than the current con-sumed by the consumers in the vehicle:- “I” discharge is the current consumed by the consumers;- “I” charge is the intensity of the current as it leaves the alternator.

The balance of the charge is the level of charge from which the discharge value issubtracted. The result should be positive. If it is negative, the alternator will not beable to meet all the electrical consumption needs, the battery is therefore drawnupon and loses charge.

Measurement of voltage

Measuring the voltage enables the proper functioning of the alternator to bechecked.

A value which is too low indicates that the alternator is not satisfying the electricalconsumption.

A value which is too high could lead to significant electrical problems with the con-sumers, particularly the computers. In such a case, the control system may befaulty.

Automated checks.

Other checks are performed by means of automatic tests using CLIP.

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CONNECTIONS ANDHARNESSES

Introduction to connections 44Disassembling?Reassembling the connections 45

Repairing connectors and harnesses 45

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Connections and harnesses

Introduction to connectionsThe theory of connections is linked to the concept of electrical connections. Itincludes in particular the elements listed below:- the connector: male (clip carrier) or female (tongue carrier)- the clamp: male (clip) or female (tongue)- the splice: bundles of several wires connected by soldering- the terminal block: bundles of several wires by crimp connection- the shunt unit: connected by solder bridging

All these components may be subjected to various constraints.

1. Tongue connector

2. Clip connector

3. Lock

4. Seal

5. Alignment slot

6. Fixing bracket

7. Heat-shrinkable sleeve

8. Sealing mastic

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Connections and harnesses

Preliminary check of the connectors

• Check the position and completeness of the connectors.

• Check that there are no interfering elements which may adversely affect theconnectors.

Disassembling?Reassembling the connectionsDisassembling

- In all cases, refer to NT 8074 (as of 01.07.2003) and MR.- Never disconnect the clip and tongue connectors by pulling on the wires.- Pay attention to the fixings of the harness to the vehicle.

- Once the connector is removed, check its condition (signs of wear, any fusedparts, wrenched centre pin, broken locking bar, damaged seal, etc.).

Refitting

- Follow the original refitting sequence in order to ensure maximum reliability.- Confirm the presence of an alignment slot and its accuracy.- Ensure that any seals are not twisted on reconnection.- When a connector is locked in place this is usually indicated by an audible sound.

Replacement or repair of harnesses

The harnesses are dealt with in the Wiring Diagrams Technical Notes. The ref-erence label may be indicated in the Wiring Diagram Technical Note, which willmake it easier to locate within the vehicle.

Repairing connectors and harnessesIt is necessary to consult the Technical Documentation and confirm that the nec-essary spare parts are available, and that it is possible to obtain a quality level atleast equivalent to the factory-fitted parts (wire diameter, fixing clips, etc.). Use theappropriate tools for the repair.

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TROUBLE SHOOTINGAND REPAIRING ANELECTRICAL CIRCUIT

Fault finding procedure 47Using the Wiring Diagram NT 49

Electrical checks. 49

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Trouble shooting and repairing an electrical circuit

Fault finding procedureStages of the fault finding procedure

1. Collection of information

2. Analysis

3. Identification of the origin of the fault

4. Elimination of the cause of the fault

5. Correction of the fault

6. Confirming the repair

Technical Documentation: MR and Wiring Diagram NT

In order to diagnose and repair an electrical fault, refer to Section 8 of the RepairManual of the vehicle, which explains the functions of the various elements of thevehicle. This provides an aid to the diagnosis.

From the available documentation it may be useful to refer to the Wiring DiagramTechnical Notes . When consulting a Wiring Diagram NT document it is necessaryto identify the vehicle by its trade name and the year model.

Technical reference material

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Using the Wiring Diagram NTThe use of the Wiring Diagrams Technical Notes is briefly explained here. Theuse of the Wiring Diagram NT is described in more detail in the Electricity level 2module.

NOTEAt the start of each Wiring Diagram NT there is a user note providing fullerinformation.

1) Index of functions

This section enables a search of the panel numbers to be made, corresponding tothe vehicle function which is faulty

2) Diagram index

The index of functions refers the reader to a batch of panels. The list of criteriaenables the correct panel, relating to the vehicle in question, to be determined.

In order to read the diagrams, the following should be carried out:- identify the power source and earth,- identify the components,- identify the connectors.

3) "Components" and "Connections" tabs

The "Components" tab allows each component to be identified by its number.

The "Connections" tab allows the "wiring routes" panel to be determined

4) Wiring routes

This section locates the electrical circuits on the vehicle. This section facilitatesthe selection of the most convenient inspection points (ease of access, relevance).

Electrical checks.Measurement of resistance

Electrical resistance is measured using an ohmmeter. The ohmmeter is connectedin parallel (or branch connection) to the part to be checked.

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In its ohmmeter function, the multimeter emits a weak current ( a few tens of mA)with a weak voltage into the circuit under investigation. On the basis of the mea-surement it detects, it deduces an electrical resistance value. It is therefore es-sential that the circuit under examination is insulated from all sources of electricalenergy.

IMPORTANT

As the ohmmeter generates a current, it is strictly forbidden to measurethe resistance of pyrotechnic elements of airbags and seatbelt pretension-ers.

Continuity testThis check enables an increase to be detected in the resistance of an electricalharness, a break in the circuit or a connection or splicing fault.

Checking the insulation between two wiresThis check enables the detection of short circuits between two wires or harnesses.

Checking the insulation with regard to the earth or + 12 V power supplyThis check enables the detection of short circuits to earth or to a DC power supply(before ignition).

Measurement of voltage

The voltage is measured using a multimeter in the voltmeter setting. The touchpoints are placed on the terminals of the element in question to determine its volt-age. This is a measurement in parallel.

The measurement of a drop in voltage enables losses of potential in a cable to bedetected. This drop in voltage is produced by an excessive resistance or a poorconnection (badly fitted or corroded terminal)

Measurement of current

The measurement of current is carried out by a multimeter placed in series in thecircuit, or by using a clamp-on probe.

The multimeter measures low-intensity currents precisely, for example leakagecurrents. The fact that it needs to be placed in series in the electrical current limitsits usefulness. The multimeter generally supports a maximum of 10 A.

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IMPORTANT

Measuring a strong current may damage the multimeter.

The clamp-on probe enables high-intensity currents to be measured. In order touse it, the circuit does not need to be opened. Nevertheless, its lack of precisionmeans that it cannot be used to measure low-intensity currents.

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QUESTIONNAIRE1. What is the symbol and unit of measurement for voltage?

A U and volt (V)

B I and ampere (A)

C R and Ohm (Omega)

D P and watt (W)

2. What is the symbol and unit of measurement for resistance?

A U and volt (V)

B I and ampere (A)

C R and Ohm (Omega)

D P and watt (W)

3. What is the symbol and unit of measurement for current?

A U and volt (V)

B I and ampere (A)

C R and Ohm (Omega)

D P and watt (W)

4. What is the current circulating in a simple circuit, comprising a power supply of12 V and a consumer with resistance equal to 4 Ohms?

A 4.8 A

B 0.3 A

C 3 A

D 48 A

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5. What is the symbol and unit of measurement for power?

A U and volt (V)

B I and ampere (A)

C R and Ohm (Omega)

D P and watt (W)

6. What is the intensity of the current in a circuit comprising a 60 W bulb with a 12V power supply?

A 72 A

B 0.5 A

C 5 A

D 720 A

7. What measurement may blow the multimeter fuse?

A Measurement of high voltage

B Measurement of a strong current

C Measurement of high resistance

8. What needs to be done when a fuse blows?

A The fuse must be replaced with a fuse of greater amperage.

B The fuse must be replaced with a fuse of lower amperage.

C The cause should be determined before replacing the fuse with one of equal amperage.

9. What is the function of a clamp-on probe?

A Measuring a strong current without opening the electrical circuit.

B Measuring precisely a current of less than 0.1 A.

C Avoiding a drop in voltage.

10. What precaution should be taken when measuring a leakage current?

A Wait a few moments to ensure that there is no delay in the power supply

B Use a clamp-on probe in order to avoid blowing the multimeter fuse

C Switch on all consumers in order to discharge the battery

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11. Above what value is a leakage current deemed abnormal?

A 0.001 A

B 0.03 A

C 0.3 A

D 1 A

12. What are the preliminary battery checks to be carried out?

A Visual inspection of the condition of the casing, the terminals and the electrical connections

B Checks using the Midtronics then the CLIP devices

C Checking the condition of the battery during ignition

13. What battery may be used to replace an original with the properties 12 V 50 Ah350 A?

A 6 V 30 Ah 300 A

B 12 V 50 Ah 400 A

C 24 V 60 Ah 500 A

D 12 V 50 Ah 300 A

14. What precautions should be taken when disconnecting the battery from a vehi-cle?

A Switch off all the consumers on the vehicle and wait for the fan assembly to stop.

B Wait for a few minutes after switching off.

C Close all the windows and doors and activate the alarm.

D Disconnect the consumer cut-out fuse.

15. What additional precaution should be taken when disconnecting the batteryfrom a vehicle equipped with the Carminat system?

A Switch on all the consumers on the vehicle.

B Wait forty seconds after switching off.

C Eject the CD from the Carminat system.

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16. What gives rise to the use of very fine ignition cables?

A Nothing unusual

B Heating up of the cables and the risk of fire

C A gain in energy for the faulty battery

D A short circuit to earth

17. What type of wiring cannot be repaired?

A The power supply wires for electric motors

B The wiring in the passenger compartment

C The injection system wiring

D Flat wires

18. On which circuits is it forbidden to undertake electrical measurements?

A The circuits linked to the injection system

B The circuits linked to the navigation system

C The airbag and pretensioner circuits

19. What operation is it impossible to carry out using the Proner pliers?

A Strip a wire.

B Cut a wire.

C Crimp a wire.

D Unclip a spliced joint.

20. Which of these colour codes is not part of the basic Renault electrical systems?

A Black

B Red

C Green

D Yellow

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21. Which checks should be carried out on the starter motor circuit?

A Visual and audible checks, and checks using a measuring device

B Visual checks, and checks using a measuring device

C Checks using a measuring device

D Checks using CLIP

22. Which parameter does not affect the ignition system of a vehicle?

A The immobiliser system

B The outside temperature

C The engine injection system

D The cooling system

23. Which checks should be carried out on the charging circuit?

A Visual and audible checks, and checks using a measuring device

B Visual checks, and checks using a measuring device

C Checks using a measuring device

D Checks using CLIP

24. Which element of the alternator is involved if the output voltage exceeds 16.2 V?

A The control system

B The rectifier

C The rotor

D The stator

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Renault Training Electricity LEV1

Documents

toothed ring

wiring diagram

renault uk

individual

electric starter

measuring

physical measuring

starter motor