Engine disassembly inspection
• With oil loss via the piston rings
A lot of carbon attaches to the outer circumference at the top of the piston.
• With oil loss via the valve guides
A lot of carbon attaches to the intake valve face, at the top of the piston, or to the exhaust valve stem. In addition, oil can also attach to these parts, making them wet.
When oil loss via the valve guides is discovered, remove the intake and exhaust valves and inspect the conditions at the face and stem.

An electrical conductor that can be moved freely is placed between the N and S (magnetic) poles of a magnet as shown in the diagram. Then, a galvanometer is connected to the conductor to complete a circuit.
When the conductor is moved between the magnetic poles as shown in the diagram, the indicator of the galvanometer swings.
Thus, when the conductor is moved between the magnetic poles, the conductor crosses and cuts off the magnetic flux, which generates a current. For this reason, if the conductor is moved parallel to the magnetic flux, no current will be generated.
This phenomenon that generates current is called an electromagnetic induction, and the current that flows through the conductor is called an induction current.
The induction current is generated by the electromotive force that is created in the conductor as a result of the electromagnetic induction. This electromotive force is therefore called an inductive electromotive force.

Direction of Electromotive Force

the relationship between the direction of the magnetic field, the direction of the inductive electromotive force, and the direction in which the conductor is moved. This relationship is generally known as Fleming’s right-hand rule.
According to this rule, the following applies when the thumb, index finger, and middle finger of the right hand are opened to form right angles:
Index finger: Direction of flux (B)
Middle finger: Direction of current (I)
Thumb: Direction of motion (F).

Amount of Electromotive Force
A conductor that moves at a constant speed in one direction, between magnetic flux lines having the same density
A conductor that moves at a constant speed in the path of a circle between magnetic flux lines having the same density
The amount of the inductive electromotive force is directly proportionate to the number of magnetic flux lines that the conductor disrupts per unit of time.
The inductive electromotive force of a conductor, which moves at a constant speed in one direction between magnetic flux lines of the same density, is the same at any point.
However, if the movement direction of the conductor is not the same, the electromotive force will vary even if the speed is constant and the magnetic flux is of the same density.
In the diagram, the conductor rotates counterclockwise around point 0, between the magnetic poles.
When the conductor is in positions 0 and 6, the direction of the magnetic flux and the movement direction of the conductor are parallel to each other. Therefore, it will not generate an electromotive force.
Conversely, when the conductor is in positions 3 and 9, the direction of the movement of the conductor crosses the magnetic flux perpendicularly. This creates the greatest amount of electromotive force.
The sine graph below represents the relationship between the movement direction of the conductor and the amount of electromotive force.

Principle of the Generator

When a single conductor rotates in a magnetic field as shown in the diagram, an inductive electromagnetic force will be generated through electromagnetic induction.
When the conductor is bent and rotated as shown in the diagram, twice the amount of inductive electromotive force will be generated.
When the conductor is formed into a coil as shown in the diagram, greater amount of inductive electromotive force will be generated. In this manner, the rotation of the conductor in the magnetic field generates an inductive electromotive force.
The greater the number of windings in the conductor, the greater the amount of inductive electromotive force that will be generated.

Alternating-current Generator

The amount and direction of the inductive electromotive force that is generated by the rotation of a coil will vary depending on the position of the coil.
In diagram (1) on the left, the current flows from brush A to the light bulb. In diagram (2), the supply of current stops. In diagram (3), the current flows from brush B to the light bulb.
Accordingly, the current that is generated by this device is an alternating current. Therefore, this device is called an alternating current generator.

Self-induction Effect
When the switch in diagram is closed or opened, the magnetic flux in the coil changes. To create the same conditions without allowing the current to flow through the coil, it will become the same as moving a magnet in and out of the coil as shown in diagram .
Moving a magnet in and out of a coil causes an electromotive force to be generated in the coil. This electromotive force is generated regardless of whether a current flows in the coil.
Thus, the magnetic flux variances that result from the flow or stoppage of current through the coil cause the same coil to generate an electromotive force.
This phenomenon is called the self-induction effect.
Mutual Induction Effect

Two coils are arranged in the diagram. When the current that flows through one coil (primary coil) is changed, an electromotive force will be generated in the other coil (secondary coil), in the direction that prevents the magnetic flux in the primary coil from changing. This phenomenon is called the mutual induction effect.
A voltage transformer utilizes this effect. A voltage transformer, which is contained in the ignition coil of a vehicle, is used to apply a high voltage to the spark plugs.
Because the magnetic flux does not change if a constant current flows through the primary coil, no electromotive force will be generated in the secondary coil.
When the primary current is disrupted by turning the switch from ON to OFF, the magnetic flux that was generated by the primary current up to that point disappears suddenly. Thus, an electromotive force will be created in the secondary coil in the direction that will prevent the elimination of the magnetic flux.
Thus, a voltage transformer allows current to flow to the primary coil, and when the current is cut off, the high voltage that is generated by the self-induction effect of the primary coil is further increased between the primary and secondary coils through the mutual induction effect.
The amount of inductive electromotive force that is generated by this device changes with the following conditions:
The changing speed of the magnetic flux:
With a given amount of change in the magnetic flux, a change that occurs within a shorter time generates a greater amount of electromotive force.
The amount of magnetic flux:
The greater the amount of change of magnetic flux, the greater the electromotive force will be.
The number of windings of the secondary coil: With a given amount of change in magnetic flux, the greater the number of windings, the greater the amount of electromotive force will be.
Thus, in order to generate a high secondary voltage, the current that flows to the primary coil should be as great as possible, and then the current should be cut off suddenly.

Click on the bulb mark or the underlined sentence.
An electrical device operates normally if there are no malfunctions in its circuit. The voltage at the connectors can be measured as shown in the diagram.
However, if an electrical device does not operate normally, its circuit may have failed in some manner.
In this case, the area of a malfunction can be identified by measuring the connectors.

Identifying the area of a malfunction
Suppose a light bulb does not illuminate (or an electrical device does not operate normally) as shown in the diagram.
By measuring the voltage in each area, it becomes evident that there is no voltage after connector A (or C).
This indicates that the conductor is disrupted at connector A (or C), which stops the flow of the current.
This type of failure is called an open circuit.

Poor Circuit
If there are no problems in the circuit, the light bulb in the circuit will illuminate brightly.
However, if the light bulb illuminates dimly, there may be a malfunction in this circuit.

Identifying the area of a malfunction
A voltage check at each end of the light bulb in the circuit has detected
9 V.
In this circuit, the normal voltage at each end of the light bulb is 12 V.
Because this is a direct current circuit, this symptom indicates the presence of a resistor other than the light bulb.
A subsequent voltage check at each end of the switch has detected 3 V.
This indicates that the switch presents resistance, possibly due to a poor contact.

Short Circuit
Supposing that the fuse has blown in the circuit, check the cause of the blown fuse.
Identifying the area of a malfunction
The function of a fuse is to prevent wiring or equipment from being damaged by opening the circuit as a result of heating and melting when excessive amperage flows through it.
For this reason, it can be assumed that excessive amperage has flowed through this circuit.
Because this is a direct current circuit in which the voltage remains constant, there is the possibility of a short circuit between the wiring harness and ground that caused the excessive amperage to flow.
Upon measuring the resistance between each connector and ground, 0 Ω has been detected at connector B.
This indicates that connector B has shorted to ground, causing an excessive amperage to flow through this circuit.

The following measurements can be performed by operating the function selector switch:
Alternating current voltage measurement
Purpose:
For measuring the voltage of household or factory power supply lines, alternating current voltage circuits, and the tap voltages of a power transformer.
Measurement method:
Set the function selector switch to the alternating current voltage measurement range and connect the test leads. The polarities of the probes are interchangeable.
Direct current voltage measurement
Purpose:
For measuring the voltage of various types of batteries, electrical devices, and transistor circuits, and the voltages and voltage drops in circuits.
Measurement method:
Set the function selector switch to the direct current voltage measurement range. Place the black, negative test lead, to the ground potential, the red, positive test lead on the area to be tested, and take a reading.
Resistance measurement
Purpose:
For measuring the resistance of a resistor, continuity of a circuit, short circuit (0 Ω), open circuit (infinity ∞ Ω).
Measurement method:
Set the function selector switch to resistance/continuity. (If the display shows “” at this time, the tester is in the continuity testing mode. Therefore, press the blue Ω/ mode selector switch to change the tester to resistance inspection mode.) Then, place a test lead on each end of a resistor or a coil to measure the resistance. Make sure that no voltage is applied to the resistor at this time. The diode cannot be measured in this range because the used voltage is low.
Continuity check
Purpose:
For checking the continuity of a circuit.
Measurement method:
Set the function selector switch to the continuity range. (Make sure that the display shows “” at this time. If it does not, press the Ω/ mode selector switch to change the tester to continuity mode.) Connect the test leads to the circuit to be tested. The buzzer will sound if the circuit has continuity.
Diode test
Purpose:
For testing a diode.
Measurement method:
Set the function selector switch to the diode test mode. Check the continuity in both directions. If the diode has continuity in one direction and there is no continuity when the test leads are interchanged, the diode is determined to be normal.
If the diode has continuity in both directions, it is shorted. If it does not have continuity in either direction, it has an open circuit.
Direct current amperage measurement
Purpose:
For measuring the amperage consumption of devices that operate with a direct current.
Measurement method:
Set the function selector switch to the amperage measurement range. Select an area for inserting the positive test lead with the proper range. To measure the amperage of a circuit, the ammeter must be connected in series to the circuit. Therefore, separate an area in the circuit in which to connect the test leads. Connect the positive test lead to the side with the higher potential and the negative test lead to the side with the lower potential, and take a reading.

A capacitor contains electrodes, which consist of two metal plates or metal films that face each other. An insulator (or a dielectric substance), which can be made of various materials, is placed between the electrodes. (In the diagram, air acts as an insulator.)
When voltage is applied to both electrodes by connecting the positive and negative terminals of a battery, the facing electrodes will become positively and negatively charged.
The electric charges will remain even after the power source has been disconnected, as the capacitor has a charging effect. When the electrodes of a charged capacitor are shorted, there will be a momentary flow of current, and the stored charge will become neutralized and disappear. Thus, the capacitor is discharged.
In addition to the charge storage function described above, a significant characteristic of a capacitor is that it prevents a direct current from flowing through.
The following are examples of circuits that utilize the charge storage function of a capacitor: A regulator circuit for the power supply, a backup circuit for the microprocessor, and a timer circuit that utilizes the length of time required for charging and discharging a capacitor. Also the circuits that utilize the characteristic of a capacitor to shut off a direct current are the filters that extract or eliminate specific frequency elements.
Using of these characteristics, capacitors are used in automotive electric circuits for many purposes, such as to eliminate noise or substitute for a power source or a switch.

REFERENCE:
A capacitor is also known as a condenser.

Charging Characteristics of Capacitor

When a direct current voltage is applied to a completely discharged capacitor, the current will initially flow at a rapid rate. After the capacitor starts to store electricity, the flow of the current diminishes. Ultimately, when the electrostatic capacity (the ability of the capacitor to store electricity) of the capacitor has been reached, the flow of the current will stop. The voltage of the capacitor at this time is equal to the applied voltage.

If the electrical circuit for devices requiring a high amperage consists of a power source, a switch, and a light bulb that are directly connected, the switch and the wiring harness must be of a high capacity that can withstand the high amperage. However, through the use of a low-amperage current, a switch can turn a relay ON and OFF, which in turn, can apply the high amperage that flows to turn the light bulb ON and OFF.

The diagram on the left describes the mechanism of a relay. When the switch closes, the current flows between points 1 and 2, thus magnetizing the coil. The magnetic force of the coil attracts the moving contact between points 3 and 4. As a result, points 3 and 4 close and allow the current to flow to the light bulb. Thus, through the use of a relay, the switch and the wiring harness to the switch can be of a low capacity.

Fuse

A thin metal strip which burns out when too much current flows through it, thereby stopping current flow and protecting a circuit from damage.

Fusible link

A heavy-gauge wire placed in high amperage circuits which burns out on overloads, thereby protecting the circuit.

Fuses in circuit diagrams appear as shown in the right side in the illustration.

Types of relays

Relays are classified into the following types, depending on how they open or close:

1. Normally open type:

This type normally opens, and closes only when the coil is energized.

2. Normally closed type:

This type normally closes, and opens only when the coil is energized.

3. Double throw type:

This type switches between two contacts, depending on the state of the coil.

An electric circuit can be divided into a series connection or parallel connection, depending on how the electrical devices are connected.
1. Series connection
With this method, multiple electric devices are connected serially with a single electric wire.
Figure represents a series connection in the form of a water flow.
The uniqueness of this water flow is that an equal volume of water flows through each of these waterfalls, which is also equal to the volume of water that flows from the source.
(I0 = I1 = I2 = I3)
Moreover, the sum of the height of the three individual waterfalls equals the height of the entire waterfall.
(V0 = V1 + V2 + V3)
2. Parallel connection
With this method, multiple electric devices are connected to a single electric wire.
Figure represents a parallel connection in the form of water flowing.
All the waterfalls have the same height.
(V0 = V1 + V2 + V3)
Moreover, the sum of the volume of the water that flows through the waterfalls is equal to the total volume of water.
(I0 = I1 = I2 = I3)

Resistance

1. Resistance of a series circuit
The combined resistance of the entire circuit is equal to the sum of the resistors in the circuit.
R0= R1 + R2 + R3

2. Resistance of a parallel circuit
The combined resistance of the entire circuit can be calculated with the following formula:
R0 = 1 / (1 / R1 + 1 / R2 + 1 / R3)
R0 is smaller than the smallest one between R1, R2, and R3

Current

1. Amperage of a series circuit
The amperage that flows through each of the electrical devices in the circuit is the same as for any other electrical device in the entire circuit.
I0 = I1 = I2 =I3

2. Amperage of a parallel circuit
The sum of the amperage that flows through the electrical devices in the circuit is equal to the amperage of the power supply.
I0 = I1+ I2 + I3

Voltage

1. Voltage of a series circuit
The sum of the voltage drops that occur with each of the electrical devices in the circuit is equal to the voltage of the power supply.
V0 = V1 + V2 + V3

Voltage
Voltage drop
While a current flows through a circuit, its voltage decreases each time it passes a resistor.
This decrease is called a voltage drop.
In the series circuit shown on the left, the power source has 12 V. The voltage that drops each time the current passes through a resistor can be calculated with the following formula:
Voltage drop when the current flows through 2 Ω resistor:
12 V x 2 Ω / ( 2 Ω + 4 Ω + 6 Ω) = 2V
Voltage drop when the current flows through 4 Ω resistor:
12 V x 4 Ω / ( 2 Ω+ 4 Ω+ 6 Ω) = 4V
Voltage drop when the current flows through 6 Ω resistor:
12 V x 6 Ω / ( 2 Ω+ 4 Ω+ 6 Ω) = 6V

2. Voltage of a parallel circuit
The voltage drop that occurs at each electrical device in the circuit is the same as any other electrical device, as well as the voltage of the entire circuit.
V0 = V1 = V2 = V3

The speed of the waterwheel changes by changing the water volume in the tank. This means that the speed of the water flowing to the waterwheel changes with the change in the water pressure in the tank.
When this phenomenon of water is substituted with electricity, the water volume (water pressure) is the voltage, and the water flow is the electrical current.

Current and resistance
The force of the water flow changes with the height of the gate that is located between the tank and the waterwheel. As a result, the speed of the waterwheel changes.
This gate is equivalent to the resistance in an electrical circuit.

Current, voltage, and resistance
Increasing the water volume in the tank increases the speed of the waterwheel. On the other hand, lowering the gate to oppose the water flow decreases the speed of the waterwheel. Thus, it is possible to operate the waterwheel at a desired speed by adjusting the water pressure and the height of the gate.
Similarly, in an electrical circuit, the desired amount of work is allocated to various devices by changing the value of the resistance or voltage.

Ohm’s Law

The following relationship exists between current, voltage, and resistance:
Increasing voltage increases the amount of current.
Decreasing resistance increases the amount of current.
This relationship can be summarized as follows: the amount of current increases in direct proportion to the amount of voltage, and decreases in inverse proportion to the amount of resistance.
This relationship between voltage, current, and resistance is defined by Ohm’s law, which is represented by the following formula:
E = R x I
E: Voltage(V)
R: Resistance(Ω)
I: Current(A)

Electric Power
Electric power is represented by the amount of work performed by an electrical device in one second.
It is measured in watts (W), and 1W is the amount of power that is obtained when a voltage of 1 V is applied to a load resistance of 1Ω, and a current of 1 A flows for one second.

The amount of power is calculated with the following formula:
P = I x V
P: Amount of power, unit: W
I: Current, unit: A
V: Voltage, unit: V
Example:
If 5A of current is applied in one second using a voltage of 12 V, the electrical device performs 60W of work. (5 x 12 = 60)
Direct Current and Alternating Current
A current of constant direction with a magnitude that does not vary is called direct current. On the other hand, a current that reverses direction and has a variable magnitude is called alternating current.
1. Direct Current (DC)
This is a type of current that flows in a constant direction, from the positive pole to the negative pole, as in an automotive battery or a dry cell.
2. Alternating Current (AC)
This is a type of current that reverses direction at regular intervals. The electricity in the household outlets or industrial three-phase power supply used in factories is some examples.

Electrical devices are used in numerous areas of an automobile, and provide various functions.
As electricity passes through a resistor, it affects the resistor and can provide a number of functions.
Electrical devices utilize those functions according to purpose by converting electricity into work.
Functions of electricity
1. Heat-generation function
Heat is generated as electricity passes through a resistor, such as a cigarette lighter, fuse.
2. Light-emitting function
Light is emitted as electricity passes through a resistor, such as a light bulb.
3. Magnetic function
A magnetic force is generated as electricity passes through a conductor or coil, such as an ignition coil, alternator, injector.

All substances are comprised of atoms, which consist of nuclei and electrons. A metallic atom contains free electrons.
Free electrons are electrons that can move freely from the atoms.
The transfer of these free electrons among metallic atoms generates electricity.
Therefore, the electricity flow through an electrical circuit is the electrons moving in a conductor.
When a voltage is applied to both ends of a metal (conductor), the electrons flow from the negative pole to the positive pole. This flow is the opposite of the flow of an electrical current.
Three elements of electricity
Electricity consists of three basic elements:
1. Current
This is the current flow through an electrical circuit.
Unit: A (ampere)
2. Voltage
This is the force of electricity that moves current through an electrical circuit. The higher the voltage, the greater the amount of current that will flow through the circuit.
Unit: V (volt)
3. Resistance
This is the opposition to the current flow.
Unit: Ω (ohm)

The hydraulic circuit in the ABS for FF vehicles is divided into front right wheel and rear left wheel system and the front left wheel and rear right wheel system as shown in the diagram. The explanation hereafter is only given for the operation of one of these systems, but the other systems operate in the same manner.

(1) During normal braking (When the system does not operate)

During normal braking, the control signal from the Skid Control ECU is not input. For this reason, the pressure holding and reduction solenoid valves are off, port (a) on the pressure holding solenoid side is opened, and port (b) on the pressure reduction solenoid side is closed. When the brake pedal is depressed, the brake fluid from the master cylinder flows through port (a) on the holding solenoid side and is directly transmitted to the wheel cylinder. At this time, the operation of check valve (2) prevents the brake fluid from being transmitted to the pump side.

(2) During emergency braking (when the ABS operates)

<1> Pressure reduction mode

The control signal from the Skid Control ECU turns on the pressure holding and reduction solenoids by closing port (a) on the pressure holding solenoid side and opening port (b) on the pressure reduction solenoid side. This passes brake fluid through the port (b) to the reservoir to decrease the hydraulic pressure on the wheel cylinder. At this time, port (e) is closed by the decent of the reservoir. The pump continues to run while the ABS is operating, so the brake fluid that enters the reservoir is drawn by the pump and returned to the master cylinder.

<2> Holding mode

The control signal from the Skid Control ECU turns on the pressure holding solenoid and turns off the pressure reduction solenoid by shutting off the port (a) and port (b). This shuts off the wheel cylinder hydraulic pressure from both the master cylinder and reservoir sides to hold the wheel cylinder hydraulic pressure constant.

<3> Pressure increasing mode

The control signal from the Skid Control ECU turns off the pressure holding and reduction solenoids by opening port (a) on the pressure holding solenoid side and closing port (b) on the pressure reduction solenoid side the same as during normal braking. This cause the hydraulic pressure from the master cylinder to work on the wheel cylinder to cause the wheel cylinder hydraulic pressure to increase.

HINT

The brake assist changeover solenoid valve is only used in vehicles equipped with BA.

Inspection method