AUTOMOTIVE ELECTRICAL TESTING · An electrical switching unit known as a "solenoid". Most modern starters are of the pre-engaged design and the solenoid is mounted directly onto the

AUTOMOTIVE ELECTRICAL

TESTING (AET)

Learner Guide

TABLE OF CONTENTS

ABOUT THIS SERIES PAGE 1 PROGRAMME AET-1: TESTING THE STARTER CIRCUIT OBJECTIVES PAGE 3 OVERVIEW OF THE STARTING CIRCUIT PAGE 4 HOW THE SYSTEM WORKS PAGE 7 STARTER TYPES PAGE 8 THE COMPLETE STARTING CIRCUIT PAGE 9 SELF-TEST NO. 1 PAGE 10 FAULT DIAGNOSIS PAGE 12 SELF-TEST NO. 2 PAGE 15 FAULT DIAGNOSIS (CONTINUED) PAGE 16 SELF-TEST NO. 3 PAGE 18 MAINTENANCE PAGE 19 PROGRAMME AET-2: TESTING THE A.C. CHARGING CIRCUIT OBJECTIVES PAGE 21 OVERVIEW OF THE A.C. CHARGING CIRCUIT PAGE 22 SELF-TEST NO. 1 PAGE 26 FAULT DIAGNOSING PAGE 27 SELF-TEST NO. 2 PAGE 30 FAULT DIAGNOSING (CONTINUED) PAGE 31 SELF-TEST NO. 3 PAGE 33 MAINTENANCE PAGE 34 MODEL ANSWERS TO SELF-TESTS PAGE 35

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ABOUT THIS SERIES This series on Automotive Electrical Testing procedures has been designed to assist you, as the learner auto mechanics and auto electricians, to do the following:

o Provide you with a practical overview of the starting systems. o Provide you with a practical overview of the charging system. o Demonstrate simple but effective procedures in testing and correcting faults that will

inevitably occur (at some time or another) in both the starting system and the charging system.

This series consists of a video programmes namely: AET-1 Testing the Starter Circuit. AET-2 Testing the A.C Charging Circuit. Accompanying the video programme is the workbook which is intended to guide you through each programme. Please read through this workbook before you view the video as this will assist you to fully understand the subjects discussed.


AUTOMOTIVE ELECTRICAL TESTING PROCEDURES

AET-1

PROGRAMME NO. 1


PROGRAMME NO. 1 THE STARTING SYSTEM

In this programme you will be given an overview of a typical automotive starting system. Following the overview we shall demonstrate how to perform a systematic check of the complete system. OBJECTIVES When you have completed this programme you will be able to:

o Identify by name all the major components of a typical starting system. o Describe the function or purpose of all components. o Using basic test instruments you will be able to "pin point" any trouble spot

anywhere in the starting system. o You will be able to rectify commonly encountered problems in the circuit.

Proceed now by first reading through the notes beginning on the following page.


PART ONE OVERVIEW OF THE STARTING CIRCUIT

The first section of the video(AET-1) covers the parts and functions of a typical (12 volt system) starting circuit. The following notes and diagrams are intended to assist you when you are performing practical work. THE SYSTEM (CIRCUIT)

1. A battery.

2. A D.C. high-torque electric motor known simply as the "starter".

3. An electrical switching unit known as a "solenoid". Most modern starters are of the pre-engaged design and the solenoid is mounted directly onto the motors "end frame" (Fig. 3a).

Inertia type starters use a remotely mounted solenoid (Fig. 3b.).


4. The fourth unit is a starter / ignition switch - a

multi-purpose switch which activates the ignition, accessories and the starter solenoid.

The diagram (Fig 5) represents how typically the four units are linked together to form the circuit. Shown alongside (Fig 6) is an electrical schematic of a typical circuit. You will notice that the four elements are connected via electric cables. The cables connecting the battery to the solenoid, and the solenoid to the starter, are "heavy" (i.e. large in the cross sectional size). These heavy cables are known as the "insulated line". In modern vehicles the insulated line is connected via the "+" (i.e. the positive) post of the battery. NB: Always connect this way if vehicle is equipped with an "alternator".


Current flow, back to source (i.e. to the battery negative), returns via the vehicles body or chassis and is referred to as the Earth, or Return Line (as shown by arrows). Note that a connecting cable, called the "bonding strap", assists to complete the earth-line on units which have engines and transmissions on rubber mountings. The bonding strap effectively "earths" the starter, which is attached to the engine" to the body.


HOW THE SYSTEM WORKS

To operate the starter ... the driver has to turn the start / ignition switch fully (usually far right). This closes the "solenoid" circuit and a low amperage current will flow into a "winding" inside the solenoid. A magnetic field builds up in the windings. Placed in this field is a plunger (metal core) which carries a "bridging contact plate" (see Fig.11). Magnetic forces react with the plunger causing it to try and move out of the field. This movement brings the bridging contact into contact with the "BAT" and "STA" terminals, which effectively closes the circuit between the battery (BAT) and the starter (STA) main terminal. Full battery current now flows across the bridging contact and into the starter "main" terminal. Upon release of the start/ignition switch ... the solenoid circuit opens and the magnetic field collapses. A strong spring returns the plunger back to its "rest" position which in turn opens the BAT and STA connection.


STARTER TYPES

1. INERTIA TYPE The starter motor is activated via the solenoid. As the motor shaft rotates a "bendix drive" is thrown into mesh with the flywheels "ring gear" (Fig.13). 2. PRE-ENGAGED STARTER In this type the solenoid is used to pull the "pinion gear" into mesh with the ring gear. This action occurs slightly before the solenoids' bridging contact closes the battery to starter main connection. A small "clutch" is normally fitted to the pinion to prevent the engine from driving the starter before it has time to disengage.


THE COMPLETE STARTING CIRCUIT

YOU ARE NOW READY TO WATCH THE VIDEO UP TO REVIEW BREAK NO. 1.

(PLEASE ENSURE THAT YOU ARE IN POSSESSION OF TECH A.V. VIDEO ENTITLED AET-1).



SELF TEST NO. 1 AET-1: PART ONE

Before we continue to the fault diagnosing procedure can you answer the following questions without looking back to the notes?

QUESTIONS YES NO

1. The four main components of a typical starter circuit are: i) _______________________________________________ ii) _______________________________________________ iii) _______________________________________________ iv) _______________________________________________

2. The insulated line consists of: i) _______________________________________________ ii) _______________________________________________

3. Vehicles with an alternator must always have the main insulated cable connected to the _____________________ battery post.

4. What is the purpose of a "bonding strap"? ANS: ________________________________________________ _____________________________________________________

5. Can you sketch a typical starter circuit? (Use the block space below)

NOW CHECK YOUR RESPONSES FROM THE NOTES.


PART TWO FAULT DIAGNOSIS

The second part of the video demonstrates the systematic procedures for conducting a full check out on a 12 volt starting system. Note that if you follow these procedures, in order, you will definitely locate any problem that may exist. Perhaps the commonest starter problem is that of the starter motor not turning or "clicking" solenoid. The procedures we shall now describe can be used whenever you suspect the problem is an electrical one, rather than a mechanical problem. PREPARATION Question: What tools and equipment will you require? Answer: Normal hand tools, a 0 – 40v voltmeter

and a hydrometer. PROCEDURE FIRST STEP Test the battery, it must be at least 70% charged, if not: Action Have the battery charged or replaced before continuing.


SECOND STEP o Ensure all connections to the battery are clean

and secure.

o Ensure all connections to the body or chassis are clean and secure.

Having ensured a charged battery and good electrical connections -does the starter motor now operate? Yes: Then you have solved the problem. No: Then move on to the next procedures. THIRD STEP Now we'll check the voltages during cranking (or attempting to).

o Connect voltmeter across both battery terminals.

(Remove L.T. wire to distributor for next tests to prevent coil overheating and engine starting).

o Crank engine (i.e. turn ignition to "start")

and observe voltage.

Reading should be no less than 9,5 volts. Action If below 9,5 volts replace battery with a known good unit and repeat test. If still below 9,5 volts then the starter motor draw is excessive. Remove starter for a full test on bench.


If battery is 9,5 volts or better move on to next step. FOURTH STEP Now we are looking for voltage at the small terminal of the solenoid.

o Connect your voltmeter as shown opposite.

o Operate the start switch and observe voltmeter (Vm).

Is the reading the same as when you checked the battery voltage? Yes: Then solenoid circuit is O.K. No: If lower, then a fault is in the ignition / starter

switch circuit. Action Check all wiring and connections and repair as necessary (see circuit opposite). FIFTH STEP Now we move along to check the voltage at the main starter terminal. Connect the Vm as shown.

• Operate ignition / starter switch and observe Vm.

Is the reading approximately the same as the battery tested voltage (i.e. no more than 0,5 volts or lower)?

Yes: Then starter circuit is O.K. No: Reading is 9 volts or less then more

testing is required.

YOU ARE NOW READY TO VIEW THE VIDEO UP TO REVIEW BREAK NO. 2.



SELF TEST NO.2 AET-1: PART TWO

Before we continue to the next of fault finding can you answer the following without referring to your notes or the video.

QUESTIONS YES NO

1. What condition must the battery be in before you can perform any checks? ANS: _________________________________________________

2. What minimum voltage should the battery give whilst the starter is being activated? (12 volt system) ANS: _________________________________________________

3. If with a new or reliable battery you still have a reading below the required voltage, what can you suspect? ANS: _________________________________________________

4. What minimum voltage should you have on the starter main terminal? (12 volt system) ANS: _________________________________________________

NOW CHECK YOUR ANSWERS.


PART TWO CONTINUED FAULT DIAGNOSING

We continue our procedural check out of the systems assuming that we obtained a lower than normal voltage at the starter main terminal, and we want to confirm that the rest of the system is in order. 1. CHECKING THE INSULATED LINE Connect your Vm across the main battery cable as shown in the diagram opposite. Operate the starter and observe voltage, which should read 0 volts. If a voltage (0,5 or more) is read, then: Action Remove and clean the terminals at both ends of the main cable and the link strap. (NB: Make sure to first disconnect battery earth thus preventing accidental flash to ground). 2. CHECKING THE SOLENOID To ensure a good internal connection of the solenoid bridge connect the Vm between the BAT and STA terminals (shown opposite). Operate the starter and check Vm. There should be a "Ov" (zero) reading. If reading is present (in excess of 0,25 volt), then: Action Replace the solenoid as the contacts are creating a resistance.


CHECKING EARTH I RETURN LINE We need make only one check which involves connecting your Vm between battery negative (-) and a good earth point on the starter motor body.

o Crank starter and observe Vm, there should be Ov (zero) reading.

o o If a reading (+0,25 volts) is present, then:

Action

o Check and clean the earth strap between battery (negative) and chassis.

o Check and clean the bonding strap terminals at both ends.




SELF TEST NO. 3 AET-1: PART TWO CONTINUED

We have now completed the system check on procedure - can you now answer the following questions?

QUESTIONS YES NO

1. If a voltage is recorded in excess of 0,5 volts across the battery positive (+) and starter main terminal what could be the problem? ANS: _________________________________________________ _____________________________________________________ _____________________________________________________

2. How would you diagnose a high resistance over the solenoid bridge contact? ANS: _________________________________________________ _____________________________________________________ _____________________________________________________

3. If a voltage is present between the battery negative terminal and the starter motor body what needs to be done? ANS: _________________________________________________ _____________________________________________________ _____________________________________________________



PART THREE MAINTENANCE

In this final section we shall describe the most usual reasons for starter circuit problems. 1. BAD ELECTRICAL CONNECTIONS

o An electrical connection is only "good" if current can flow, un-resisted, between connections.

o Anything that gets in the way of the flow is called a resistance.

o Resistance can be caused by dirt, corrosion, paint etc.

o A loose connection results in a gap and the current has to try and "jump" the gap -resulting in a spark and then erosion.

o The low voltage (12v) cannot jump a large gap -so a loose connection usually just cuts the circuit -a common problem.

Remedy

o Make a point of keeping all electrical connections clean and tight.

o Scrape away paint to reveal a bright metal surface for terminals on chassis or body.

o Coat secured terminals with petroleum jelly (Vaseline), grease or "battery-post gel" to keep out moisture

BATTERY An old or neglected battery is often the cause of most electrical problems. Unless a battery is at least 70% charged it cannot supply the high amperage required by the starter motor. Only a full battery test can reveal the batteries condition and "capacity". To learn about this you'll have to work through Tech A.V.'s battery maintenance programme (LAB series). Our final tip is this -unless the battery is reliable don't even bother to carry on testing any electrical system as all electrical test begin at the battery.


AUTOMOTIVE ELECTRICAL TESTING PROCEDURES

AET-2 PROGRAMME NO. 2


PROGRAMME NO. 2 THE A.C. CHARGING SYSTEM

In this programme you will be given an overview of a typical automotive charging system featuring the AC. generator most commonly known as the alternator charging system. Following the overview we shall demonstrate how to perform a systematic check of the complete system. OBJECTIVES When you have completed this programme you will be able to:

o Identify by name all the main components of a typical AC. charging system. o Describe the function or purpose of the main components. o Use basic test equipment in diagnosing faults to eliminate any "hit and miss"

methods. o Rectify the most commonly encountered "on vehicle" problems that occur in AC.

charging systems. Proceed now by first reading through the notes beginning on the following page.


PART ONE OVERVIEW OF THE A.C. CHARGING SYSTEM

The first section of the video (AET-2) covers the parts and functions of a typical A. C. charging system on a 12 volt supply. The following notes and diagrams are basically a replica of the video input and are intended to assist you whilst you are performing any practical work. THE BASIC CHARGING SYSTEM The principle component of the system is the "alternator", which has nowadays largely superseded the old fashioned "generator". Alternators produce an "alternating current" which, through a rectifier is converted to a direct current (D.C.) in order to:

o Maintain an acceptable "stage of charge" within the automotive battery.

o Balance the varying electrical loads when the vehicle is operating.

A typical alternator consists of two major components namely:

o A rotor (Fig.2). o A stator (Fig.3).


A complete alternator is depicted in section view here in Fig.4.

A small (low amperage) current is fed into the rotor coil via "brushes" which bear upon "slip rings". Current flowing through the rotor windings induces a magnetic field into the interlocking segments (Fig.5). This magnetic field is induced into the "stator windings" resulting in a current output (see Fig.3) from three separate leads. Three separate coil "pairs" result in an overlapping 3 phase output which now must be converted to D.C. The devise responsible for converting 3 phase A.C. current into a single output "D.C." current is known as the "rectifier" (Fig.6). Rectification of A.C. current is achieved using electronic devises called diodes. A diode is basically an electrical "one way valve" which permits current to flow through it in only one direction.


The "symbol" for a diode, as seen in electrical circuit diagrams, is shown in Fig.8. The diagrammatic circuit for a typical "rectification" process is shown in Fig.9. It must be understood that all A. C. systems are used only on NEGATIVE earth circuits. If you happen to fit the battery the wrong way round (i.e. Positive to earth) the rectifier will be instantly destroyed! (See Fig.10). In operation the battery requires differing amounts of charge ego after a start the battery requires a high charge and the output from the alternator needs to be increased. On a long run, without using lights etc. the battery will no longer need so much charge -in this case the alternator must reduce its charge-rate. The devise used to take care of this detail is the "voltage regulator". The "regulator" effectively "senses" battery voltage -then electronically reduces, or increases, the current flowing into the rotor field. Any


reduction to field current results in a reduction of alternator output. Conversely, an increased field current results in an increased alternator output. As a "driver" aid -a dash warning lamp will light up when:

i) The ignition is switched on (engine not started).

ii) A fault occurs during the running of the

engine.

iii) The warning light or "charge-indicator" is fed via the ignition circuit. It also receives a feed from the alternator field (see diagram in Fig 13).

In simple terms, the voltage flowing to the warning lamp from the ignition switch ... becomes matched by the voltage in the field circuit. At such time the potential (voltage drop) across the warning lamp reaches zero and the lamp goes out.

THIS CONCLUDES THE BASIC OVERVIEW. YOU ARE NOW READY TO VIEW THE VIDEO UP TO REVIEW BREAK NO. 1.

(PLEASE ENSURE THAT YOU ARE IN POSSESSION OF TECH A.V. VIDEO ENTITLED AET-2.)



SELF TEST NO. 1 AET-2: PART ONE

Before you continue to the fault diagnosing sequences, can you answer the following questions without looking back at your notes?

QUESTIONS YES NO

1. The rotor's functions are to? ANS:______________________________________________

2. Current is fed into the rotor windings via? ANS:______________________________________________

3. An alternators output current is created within the? ANS:______________________________________________

4. What devise is responsible for converting the A.C. into D.C.? ANS:______________________________________________

5. What are the principle (i.e. main) components in the devise you answered in question No.4? ANS:______________________________________________

6. How can you simply describe the component that you answered in question NO.5? ANS:______________________________________________

7. Why must you never connect a battery in such a way that is positive goes to earth? ANS:______________________________________________


8. What is the primary function of the voltage regulator? ANS:______________________________________________

9. In effect what does the regulator have to do to achieve your answer to question NO.8? ANS:______________________________________________



PART TWO FAULT DIAGNOSING

The second part of the video programme deals with testing of the A.C. charging system, which is simply another way of saying "fault diagnosing". The procedures that we recommend will fully check out the complete system and you will no doubt be able to isolate any problem if you stick to the procedure. PREPARATION You will require the following tools and / or equipment:

o A voltmeter (scale 0 -40 volts). o An ammeter (scale 0 -100 amps). o A hydrometer.

NOTE: Induction ammeters may not be reliable or accurate enough for some of the tests. PROCEDURE CHECK NO. 1

o Test the battery and ensure that it is at least 70% charged (refer to TECH A.V programmes L.A.B.).

o Ensure all electrical connections to the battery (insulated line and return line) are clean and tight.

CHECK NO. 2: DRIVE BELT (FAN BELT) Ensure that the belt is:

o In good condition. o Correctly tensioned.

NOTE: A loose belt will result in decreased alternator output. An over tightened belt will overload the alternator bearings.


CHECK NO. 3: ALTERNATOR CONNECTIONS Ensure that all connections to the alternator are clean and secure. NOTE: Loose or dirty connection will reduce alternator output. CHECK NO. 4: CONTINUITY OF WIRING

o Connect your voltmeter to a good earth point on frame or chassis. o Remove both connections from alternator. o Switch on ignition. o Probe each connection with + Vm lead.

Conclusion: A voltage (equivalent to battery voltage) should be found at the

output and indicator (field) leads. Corrective Action: If no voltage found, then check for open circuits. On the "ind" lead

check that the indicator bulb has not blown. A simple test to see if the indicator bulb is functioning -ground the small lead and observe if lamp comes on when ignition key is in the "on" position. CHECK NO. 5: CHECK OUTPUT CURRENT Connect your ammeter between the alternator output terminal and the "BAT" terminal on the starter solenoid / or battery positive. (Alternatively connect directly between + and the removed lead "B" in diagram). If alternator has a multi-plug connector use a jumper lead to connect IND wire to INO terminal "C" in diagram.

o Switch on vehicle headlamps for ± 3 minutes to drain surplus off battery.

o Start engine and hold revs around ± 3000 r.p.m. whilst observing the


ammeter (keep lights on). o Note the highest ammeter reading obtained as the rev's climb up.

Conclusion A reading of 30 amps or higher indicates a "healthy" alternator. NOTE: This figure will differ from model to model so check manufacturer’s specifications. A reading below 25 amps means that the alternator requires a full bench test or overhaul.

YOU ARE NOW READY TO VIEW THE VIDEO PROGRAMME UP TO REVIEW BREAK NO. 2.



SELF TEST NO. 2 AET-2: PART TWO

Before continuing with the video, can you answer the following, without referring to your notes?

QUESTIONS YES NO

1. List the first 5 checks we must perform to diagnose an alternator / circuit problem. i) ____________________________________________ ii) ____________________________________________ iii) ____________________________________________ iv) ____________________________________________ v) ____________________________________________

2. What voltage should be obtained at the two alternator connections? ANS:______________________________________________

3. At ±3000 revs what amperage should be available from the alternator output? ANS:______________________________________________



PART TWO (CONTINUED) FAULT DIAGNOSING

We continue with the basic fault diagnosing procedure. CHECK NO. 6: VOLT DROP / RESISTANCE

o Connect Vm between Alt. output terminal and battery positive (+) terminal.

o Switch on headlamps (and other loads) then start the engine.

o Hold rev's at +/- 3000 r.p.m. and observe voltmeter.

Conclusion

o Vm reading below 0,5 volts means the system is O.K. o Vm reading 0,5 volts or more means excess resistance in insulated line.

Action Check, clean and secure all insulated line terminations. CHECK NO. 6 (CONTINUED) The second part of Check No. 6 is to check the earth / return line.

o Connect Vm between battery negative (-) and alternator frame. o Switch on headlamps and run engine around +/-3000 r.p.m.'s. o Observe Voltmeter.

Conclusion Zero volts means earth / return line O.K. Any voltage means poor electrical connections on earth / return line. Action Clean and secure all earth terminations.


CHECK NO. 7: REGULATOR TEST o Disconnect main alternator lead (indicator /

field wire remains attached). o Connect ammeter between alternator

terminal and "BAT" on solenoid. o Connect Vm across the battery. o Switch on headlamps (full) and run engine. o Bring rev's up to ± 3000 r.p.m. and observe

ammeter. When amps drop to just below 10 amp read the voltmeter.

Conclusion

o Voltage should be 13,5 to 14,5 bolts. o Voltages below or above these figures indicate a faulty regulator.

NOTE: Figures quoted above are typical only, consult manufacturer’s specifications wherever possible.




SELF TEST NO. 3 AET-2: PART TWO

Before continuing with the video, can you answer the following questions without reference to the notes?

QUESTIONS YES NO

1. What is the maximum volt reading allowable across the main alternator I battery lead? ANS:_________________________________________________

2. If a higher voltage is indicated, what should you do? ANS:_________________________________________________

3. On the earth or return line what voltage should you read when running the engine? ANS:_________________________________________________

4. If you don't get the desired voltage, what do you have to do? ANS:_________________________________________________

5. What voltage range should be read across the battery when you perform a regulator test? ANS:_________________________________________________

NOW CHECK YOUR ANSWERS BEFORE TURNING TO NEXT SECTION.


PART THREE MAINTENANCE

To help avoid problems in the charging circuit and to ease the "pain" of trouble-shooting follow these simple rules. RULE 1 Take the time to physically check all electrical connections for a good, secure joint. RULE 2 Make sure that the battery is in good physical and electrical condition, if necessary:

o Clean the casing. o Clean the terminals. o Top up the electrolyte. o Re-charge the battery.

RULE 3 Use reliable test instruments and take good care of them. This concludes the Automotive Electrical Test Procedures series. Model answers for the self-test exercises for programme AET-1 & AET-2 can be found over the page.


MODEL ANSWERS FOR SELF TESTS SELF TEST NO. 1 (PROGRAMME AET-1 : PART ONE)

QUESTIONS YES NO

1. The four main components of a typical starter circuit are: i) A battery. ii) A starter. iii) A solenoid. iv) A starter / ignition switch.

2. The insulated line consists of: i) The main (+) battery cable. ii) The starter “link”.

3. Vehicles with an alternator must always have the main insulated cable connected to the positive battery post.

4. What is the purpose of a "bonding strap"? To provide a return path for the starter (body).


SELF TEST NO. 2 (PROGRAMME AET-1 : PART TWO)

QUESTIONS YES NO

1. What condition must the battery be in before you can perform any checks? At least 70% charged.

2. What minimum voltage should the battery give whilst the starter is being activated? (12 volt system) 9.5 Volts.

3. If with a new or reliable battery you still have a reading below the required voltage, what can you suspect? A faulty starter.

4. What minimum voltage should you have on the starter main terminal? (12 volt system) 9.0 Volts.



QUESTIONS YES NO

1. If a voltage is recorded in excess of 0,5 volts across the battery positive (+) and starter main terminal what could be the problem? Dirty or loose connections along the insulated line.

2. How would you diagnose a high resistance over the solenoid bridge contact? If a reading of 0.25v or more was read across both BAT and STA terminals.

3. If a voltage is present between the battery negative terminal and the starter motor body what needs to be done? Clean and secure all connections on the return line.


SELF TEST NO. 1 (PROGRAMME AET-2 : PART ONE)

QUESTIONS YES NO

1. The rotor's functions are to? Create a magnetic field.

2. Current is fed into the rotor windings via? Brushes to the slip-rings.

3. An alternators output current is created within the? Stator / windings.

4. What devise is responsible for converting the A.C. into D.C.? Rectifier.

5. What are the principle (i.e. main) components in the devise you answered in question No.4? Diodes.

6. How can you simply describe the component that you answered in question No.5? It is an electrical “one way valve”.

7. Why must you never connect a battery in such a way that is positive goes to earth? It will destroy the rectifier.

8. What is the primary function of the voltage regulator? To “regulate” the charge into the battery.

9. In effect what does the regulator have to do to achieve your answer to question No.8? It reduces or increases the field current thereby reducing or increasing the output of the alternator.



QUESTIONS YES NO

1. List the first 5 checks we must perform to diagnose an alternator / circuit problem.

i) Test the battery. ii) Adjust the belt. iii) Check alternator wire connection. iv) Continuity check of wiring. v) Check alternator output.

2. What voltage should be obtained at the two alternator connections? The same as battery voltage.

3. At ±3000 revs what amperage should be available from the alternator output? Approximately 30 amps or more.


SELF TEST NO.3 (PROGRAMME AET-2 : PART TWO)

QUESTIONS YES NO

1. What is the maximum volt reading allowable across the main alternator I battery lead? 0.5 Volts.

2. If a higher voltage is indicated, what should you do? Clean, repair or tighten all connections on the insulated line.

3. On the earth or return line what voltage should you read when running the engine? Zero.

4. If you don't get the desired voltage, what do you have to do? Clean, repair and secure all ground terminals.

5. What voltage range should be read across the battery when you perform a regulator test? Between 13.5v and 14.5v.

Documents

AUTOMOTIVE ELECTRICAL TESTING · An electrical switching unit known as a "solenoid". Most modern starters are of the pre-engaged design and the solenoid is mounted directly onto the