Design and Function - Miscellaneous Systems: Other Volvo V40 I рестайлинг

A battery works as follows

The battery consists of several cells. Schematically, a battery can be said to be made up of two electrodes, one positive and one negative. These electrodes are different materials, which are submerged in a container filled with electrolyte, often called battery acid. As a result of the different electrode materials, there is an electrical charge between the positive and negative electrodes. There is a chemical reaction between the electrodes and the electrolyte causing electrical energy to be generated. If the positive and the negative poles of the electrodes are connected to form a closed circuit, a current flows through the circuit.

In a lead accumulator, the positive electrode consists of lead oxide and the negative electrode of porous lead. The electrolyte consists of diluted sulfuric acid (H 2 SO 4 ) which is a mixture of concentrated sulfuric acid and distilled or deionized water.

Battery types

In principle, lead batteries can be divided into two different categories

1. Open batteries
2. Sealed batteries

Open batteries

In principle, open batteries have free-hanging plates in the battery box, most often insulated from each other by the negative plate being located in a small separator bag of polyethylene. The electrolyte is highly viscous and can flow freely between the plates.

A maintenance-free battery is normally an open battery where the design has reduced the gas and also has made the battery box so airtight that any gases stay in place. A lot of acid means that the fluid will last for its service life without topping up.

Sealed batteries (recombination batteries)

For sealed batteries the battery box is designed as a pressure vessel with relief valves and go under the name VRLA (Valve Regulated Lead Acid), that is, valve-controlled lead-acid batteries.

If you shut in the acid and hydrogen gas then these can react with each other and be reformed to water. This is called recombination and is a good way to almost completely eliminate fluid losses. It is not possible to shut in and recycle everything, but it can be reduced significantly. The sealed batteries can be divided into two groups

1. Gel batteries
2. AGM-batteries

Gel batteries

A gel battery has a few substances, often silicone compounds, added in the electrolyte so that it gels. Thus there is no free-floating acid that can run out of the battery.

Gel batteries have good capacity, but due to the slightly higher resistance in the low viscosity acid, they may be limited as start batteries. They can handle deep cycle discharges very well, that is, when you slowly discharge the batteries a lot several times.

Gel batteries are very rugged and are often used, e. g., in cleaning machines and golf carts.

The small volume of electrolyte in the battery and that it is low viscosity makes the battery sensitive to dehydration that an overcharge with resulting gas generation could entail.

AGM-batteries

In AGM-batteries the electrolyte is kept in place by the separator paper, consisting of a fiberglass mat (AGM = Absorbed Glass Mat), working as a "sponge". The capillary forces in the separator means that electrolyte ends up in the right place. The batteries can be built with very thin separators, which keeps down the internal resistance. This means that you can get high power from a small volume, making it perfect as start battery.

The fiberglass mat is quite thin, which makes for a small electrolyte volume in the battery. This makes the battery sensitive to dehydration that an overcharge with resulting gas generation could entail.

Properties (a few typical properties)

Scheme 20

Battery

1. Handle (on certain battery models)
2. Plugs (not maintenance-free as well as AGM-batteries)
3. Positive and negative posts.

The battery is in a plastic container and has six internal chambers, one for each cell. These chambers are not connected to each other. This means that the electrolyte level can drop in one chamber without affecting the level in the other chambers. The cells are connected in series by a sealed joint between each chamber.

On the top of some "open" batteries, there is a cover with six plugs, one for each cell. The plugs can be opened to check electrolyte level and for topping up with battery water. Maintenance-free batteries as well as AGM-batteries do not have these plugs and therefore cannot be topped up with battery water.

The battery is filled with electrolyte. The electrolyte consists of diluted sulfuric acid (H 2 SO 4 ) which is a mixture of concentrated sulfuric acid and distilled or deionized water. Electrolyte is often referred to as battery acid. Electrolyte has a density of 1.28 g/cm 3 when the battery is fully charged.

A battery is built up of two or more cells connected in series depending on which terminal voltage is desired. An open car battery consists of six cells and the terminal voltage of a fully charged battery is 12.72 V, that is 2.12 V per cell. For AGM-batteries, the max. terminal voltage of a fully charged battery is 12.93 V.

The AGM-batteries' container is provided with a safety valve. The purpose is to protect the battery against too high pressure inside the battery. Too high pressure can occur in case of incorrect charging, e. g., with too high voltage.

Note. The battery is damaged if the safety valve has been activated.

Evacuation hose (not sealed batteries)

Certain batteries (such as genuine Volvo batteries) have an evacuation hose. This applies to car models where the battery is located in the cargo compartment (not in the engine compartment). The function of the evacuation hose is to lead any gases (oxyhydrogens) that build up in the battery during charging away from the cargo compartment out into the open air.

Scheme 21

The construction of the cells

1. Positive plate in separator
2. Negative plate
3. Positive and negative plate assembly
4. Connection
5. Plate assembly for one cell.

A cells consists of several positive and negative plates. These plates are welded together in groups by plate straps. These plates function as electrodes in the cell. Each positive cell is in a type of isolator, known as a separator. The task of the separator is to separate the positive and negative plates and to catch any particles that have detached from the positive plate, thus preventing short-circuits. Each cell contains a combination of such plates connected in series. The separators consist of an acid resistant plastic.

For AGM-batteries, the pocket separator consists of a thin fibre-glass mat (AGM = Absorbed Glass Mat).

Each plate is made up of a grille with an external layer of active material. This active material contributes to the electrochemical process during charging and discharging. The grille is constructed of a type of a lead alloy which functions as a conductor for the active material and also carries the current. The positive plate has an external layer of lead dioxide, while the external layer on the negative plate consists of porous lead.

The cell is surrounded by electrolyte. This is the final component of a complete cell. Each cell can generate 2.12 V (full charge at 25°C (77°F).

For AGM-batteries, each cell can generate 2.155 V.

Scheme 22

The process during discharge

1. Negative plate: Pure lead is converted to lead sulfate
2. Electrolyte: The sulfuric acid is converted to water
3. Positive plate: Lead oxide is converted to lead sulfate
4. Power consuming components.

During discharge, the lead in the negative plate is converted to lead sulfate (PbSO 4 ).

The lead dioxide (PbO 2 ) in the positive plate is also converted to lead sulfate. During the discharge process, sulfuric acid (H 2 SO 4 ) is consumed while water (H 2 O) is created. This reduces the density of the electrolyte.

The density drops throughout the discharge process and can be gauged to determine the condition of the battery. The electrolyte in a fully charged battery has a density of 1.28 g/cm 3 . The density of the electrolyte in a fully discharged battery is 1.10 g/cm 3 .

Scheme 23

The process during charging

1. Negative plate: Lead sulfate is converted to pure lead
2. Electrolyte: Water is converted to sulfuric acid
3. Positive plate: Lead sulfate is converted to lead oxide
4. The power supply from the generator or the external battery charger.

During charging, energy is supplied to the battery. This causes an electro-chemical process that is the reverse of the process during discharge. The lead sulfate (PbSO 4 ) in the negative plate is converted back to pure porous lead (Pb) and the lead sulfate (PbSO 4 ) in the positive plate is converted to lead dioxide (PbO 2 ).

Water (H 2 O) is consumed during the charging process. Sulfuric acid (H 2 SO 4 ) is formed. The density of the electrolyte increase as the amount of sulfuric acid increases.

AGM-batteries may be charged with a max. voltage/current as follows.

* Max. current is calculated with the following formula (Battery capacity Ah/20)*5. For example, for a battery with capacity 70 Ah: (70/20)*5= 17.5 A.

** Charging time depends on how discharged the battery is, however, max. 24 h.

Scheme 24

Gas build up

1. Gas build up at the plates
2. Negative plate
3. Electrolyte
4. Positive plate
5. The power supply from the generator or the external battery charger.

Gas builds up at the end of the charging process when charging a lead battery. When the battery has reached 85-90% of the maximum capacity, the water in the electrolyte begins to separate into oxygen (O 2 ) and hydrogen (H 2 ). Oxygen is formed at the positive plate and hydrogen at the negative plate.

Gas build up results in a loss of some of the gas from the battery, because the battery must not be fully sealed. Because the water is lost, the electrolyte level in the battery will drop. New distilled or deionized water must therefore be added to prevent damage to the plates as a result of the electrolyte level being too low. If new water is not added when necessary, the plates may come into contact with the air. This would result in corrosion, reducing the capacity of the battery.

For maintenance-free batteries as well as sealed batteries (AGM), normally no gases are released. This means that the battery water is not consumed in the electrolyte and topping up of battery water is not necessary. Also, the design of the battery box does not permit topping up of battery water.

Note. Make sure that ventilation is good.

Scheme 25

Example of self-discharge (for open battery type) depending on battery temperature and discharge time

1. A. Acid density in g/cm 3
2. B. Number of days that the battery was not under load
3. C. Acid density at different battery temperatures.

There is always some self-discharge in a battery, when the battery is not in use and during both charging and discharging. If a battery is not used for a longer period, there is considerable self-discharge. The acid density falls and the active material in the plates is converted to lead sulfate. Excessive discharge must be avoided because otherwise there is an increased risk of sulfation. Sulfation may cause permanent damage to the battery. Regular charging of the battery will prevent sulfation. See Sulfation . There is an increased risk of damage from freezing in a heavily discharged battery. See Deep discharging .

The speed of discharge depends on the temperature, time, the condition and construction of the battery. The temperature is particularly influential. The rate of self-discharge is faster at higher temperatures. Batteries should be stored for prolonged periods in a dry, cold place, preferably below freezing.

Ensure that the battery is fully charged if it is to be left unused for a long period. No further charging will be required if the battery is in good condition and is stored in a dry cold place. If the battery is being stored in a warm place, it may require regular charging.

The illustration shows an example of how quickly a battery (of open type) can self-discharge, depending on the temperature of the battery. Note how the density of the acid reduces with time and how the self-discharge speeds up as the temperature increases. For an explanation of the density of the acid, see Acid density .

Scheme 26

Example of the variation in the stand-by voltage and in the density of the acid with the state of charge in a battery (of open type) at +25°C (77°F) (measured after approx. 2 hours charging or discharging)

1. A. Stand-by voltage in V
2. B. Acid density in g/cm 3
3. C. State of charge, SOC, in %
4. D. Variation in the stand-by voltage with the state of charge
5. E. Variation in the density of the acid with the state of charge.

The density of the acid is a unit showing the concentration of sulfuric acid in the electrolyte. The density of the acid is a measurement of the battery voltage and State of charge, SOC . The density of the acid is measured in g/cm 3 . Sulfuric acid is required for the chemical processes in the battery.

The higher the value of the acid (i. e. high concentration of sulfuric acid), the higher the voltage and state of charge. A low acid density value means a correspondingly low concentration of sulfuric acid, low voltage and a reduced capability for providing current. The electrolyte in a fully charged battery has a density of 1.28 g/cm 3 at +25°C (+77°F). The density of the electrolyte in a fully discharged battery is 1.10 g/cm 3 or lower depending on the type of battery.

The illustration shows how the stand-by voltage and the density of the acid drops as the state of charge of a battery reduces.

HINT: For maintenance-free as well as sealed batteries (AGM) the battery acid cannot be accessed and thus its density cannot be measured.

State of charge, SOC

The state of charge (SOC) is expressed as the amount of electrical energy that is stored in the battery at any given time, in relation to how much energy can be stored in a fully charged battery. The state of charge is listed as a percentage of full charge.

Battery service life

The service life of the battery depends primarily on its construction, maintenance and operating conditions. The following factors may shorten the service life of the battery

1. See «High temperatures»(ref-441295-S35429618492011121500000)
2. See «Cycling»(ref-441295-S25579666422011121500000)
3. See «Low electrolyte level»(ref-441295-S03470893032011121500000)
4. See «Deep discharging»(ref-441295-S29933266902011121500000)
5. See «Incorrect charging»(ref-441295-S35309355802011121500000)
6. See «Sulfation»(ref-441295-S27247505272011121500000)
7. See «Corrosion»(ref-441295-S30473999322011121500000)
8. See «Vibrations»(ref-441295-S18474381232011121500000)

To maintain the best possible service life and capacity, the battery must be maintained and charged in accordance with Volvo's recommendations.

High temperatures

A high ambient temperature speeds up the chemical processes in the battery during charging and discharging. For every 10°C (18°F) increase in temperature, the reaction speed of the processes doubles. The risk of corrosion, self-discharge and sulfation increase at a high temperature and the service life of the battery is reduced. The service life of a battery improves in colder surroundings.

Cycling

Cycling means all the discharging and charging in a battery. A battery is always cycling. Discharging, or cycling, can have varying degrees of depth. Deeper discharge is more damaging than lesser discharge. Each discharge results in stress to the plates which deteriorate accordingly. Each instance of cycling cause the material in the plates to become more fragile and ultimately some of this material will separate from the plates. Cycling results in a reduction of capacity.

A lead battery cannot tolerate infinite cycling. Deep discharges should be avoided in order to maintain as long a service life as possible.

Low electrolyte level

The electrolyte level in an open battery (not maintenance-free battery and AGM-batteries) must be checked regularly. The water in the electrolyte is consumed by gas production and absorption. Batteries have different water consumption. This depends on design and ambient temperature. The water is used more quickly in hot climates.

If the electrolyte level is too low, the battery may suffer corrosion and the capacity of the battery may be reduced. Corrosion may occur in the connections between the cells. The consequence may be an open-circuit in a connection which will prevent the battery from supplying a current.

The capacity of the battery is reduced if the electrolyte level is so low that some of the surface of the plates are not submerged in electrolyte. Such surfaces cannot contribute to the chemical processes that occur during charging and discharging.

Deep discharging

The acid density in a deeply discharged battery is very low (nearly all the sulfuric acid has been consumed and almost pure water remains. There is a high risk that the battery will be damaged beyond repair by freezing at relatively mild temperatures.

The table shows the freezing point of electrolyte in relation to the degree of charge of the battery.

The freezing point of the battery in relation to the degree of charge

A deeply discharged battery can also hydrogenate .

Hydrogenation

If the discharge is extremely deep, ultimately all the sulfuric acid will be consumed and only water will remain in the electrolyte.

Where lead sulfate is more soluble in water than in sulfuric acid, some of the lead sulfate in the plates will fall into the electrolyte. When the battery is charged, lead will fall on to the negative plates and separators. Lead gathers in small spots on the surface. This can cause short-circuits. This is known as hydrogenation.

Incorrect charging

Incorrect charging may result in permanent damage to the battery. Incorrect charging may be, for example, charging using a current/voltage that is so strong that the temperature of the electrolyte increases or that the gas development is too powerful.

Increased electrolyte temperature

If charging occurs with an extremely high current, the temperature of the electrolyte will increase considerably as the battery begins to reach full charge. Excessive temperature may damage the materials in the battery and increase the risk of short-circuits.

Intensive gas development

If the gas development during charging is extremely intensive, some of the particles may be forced loose from the active materials on the plates. The plates suffer wear, reducing the service life and capacity. Short-circuits may occur as released particles drop to the bottom of the cell container or cross to the opposite plate.

To ensure optimal performance, always charge batteries according to Volvo's instructions.

Scheme 27

Lead sulfate is formed on the plates during discharge. Normally small crystals are formed, which then revert to lead and lead oxide when the battery charges.

In certain circumstances during discharge, large insoluble crystals of lead sulfate may be formed. These crystals may form an insulating layer on the plates. This reduces the effective surface of the plates, reducing the contact between the active materials on the plates and the electrolyte. As a result, the capacity of the battery reduces considerably. This is called sulfation and is a result of a battery being left standing for a long period (in excess of two weeks) at a low charge, or because the battery has been under charged repeatedly.

The plates always expand slightly during discharge. If the discharge is very slow, the expansion may be so great that the plates deform or crack. Such damage is permanent and the battery cannot be used again. If a battery has undergone excessive sulfation, it may be possible to renovate the battery by charging the battery slowly using a very low current.

Regular maintenance charging will prevent sulfation.

Corrosion

Batteries may corrode in hot conditions, particularly in countries with hot climates. At high temperatures, the grille in the cell plates corrodes and becomes porous. The connections between the plates may also corrode. The result is a reduction in conductivity and therefore capacity.

AGM-battery

For AGM-batteries, the pocket separator consists of a thin fibre-glass mat (AGM = Absorbed Glass Mat).

See: Separator

Active material

The active material consists of lead oxide in the positive plates and porous lead in the negative plates. The active materials react with the sulfuric acid in the electrolyte during charging and discharging according to the following chemical reaction

PbO 2 + Pb + 2 H 2 SO 4 = 2 PbSO 4 + 2 H 2 O

Ampere (A)

Unit for electrical current. Abbreviated to A.

Ampere hours (Ah)

Unit of measurement used to measure the ability of the battery to store electricity or the capacity. The storage capacity is obtained by multiplying the outflowing current in amperes by the discharge time in hours. Ampere hours are abbreviated to Ah.

Example

A battery that supplies 3 amperes for 20 hours provides 3 A x 20 h = 60 Ah.

Battery acid

Another name for electrolyte. See Electrolyte .

Battery water

Battery water is distilled or deionized water and must be used to top up the battery if the electrolyte level is low. Regular tap water must not be used because it contains substances which may damage the battery.

For maintenance-free batteries as well as sealed batteries (AGM) it is not possible to fill battery water.

CCA

Abbreviation of Cold Cranking Amperes. The Cold cranking amperes of a battery is expressed using the CCA value.

Electro-chemical current producing unit in a battery. Consists of a package with positive and negative plates, separators and electrolyte enclosed in a shell. A fully charged lead battery with a stand-by voltage of 12.72 V has six cells.

Cycle

In a battery, a cycle consists of a discharge phase and a charge phase.

DIN

An industry norm. Abbreviation of Deutsche Industrie-Norm.

Electrical current

A current is a flow of electrodes moving in a cable. It can be compared with a stream of water. Electrical current is measured in amperes (A).

Electrode

An electrode is the place where the chemical reactions during discharge and charge take place. A cell consists of at least one positive and one negative electrode. During discharge, lead oxide is converted to lead sulfate at the positive electrode. At the negative electrode, porous lead is converted to lead sulfate. During charging, the reactions are in the opposite direction; lead dioxide and porous lead are reformed. Electrodes also transport current. In a battery, the electrodes are normally called plates.

Electrolyte

In a lead battery, electrolyte consists of concentrated sulfuric acid and distilled water. Electrolyte is a liquid that conducts current and adds hydrogen and sulfate ions to the electro-chemical reaction during charging and discharging

PbO 2 + Pb + 2 H 2 SO 4 = 2 PbSO 4 + 2 H 2 O

Separator

A type of plastic insulator enclosing each positive plate in the cell. The roll of the separator is to separate the positive and negative plates from each other and to catch particles that detach from the positive plate to avoid short-circuits.

For AGM-batteries, the pocket separator consists of a thin fibre-glass mat (AGM = Absorbed Glass Mat).

Grid

A lead alloy frame construction on each plate in the battery. The grid functions as a carrier of the active materials, lead oxide and porous lead, which contribute to the electro-chemical processes during charging and discharging. The grid also conducts the current in the cell.

A destructive chemical reaction when metal is broken down in an aggressive chemical environment. Sulfuric acid, for example, is aggressive against iron. The iron breaks down and corrodes. The battery terminal is vulnerable to corrosion if it is not maintained correctly.

Short-circuit

A short-circuit is when the current takes a short cut where the resistance is less and therefore does not go via the intended route. A short-circuit can be caused for example by particles detaching from the plates in the cells. Eventually these deposits can be so large that a conductive connection is made between the two plates so that the current can flow between the two plates instead. A short-circuit in a cell can fully discharge a battery and render the battery useless.

Cold cranking amperes

A measurement of the ability of the battery to start the car. The cold cranking amperage is expressed as a CCA value. Volvo batteries are usually marked with a CCA value according to the SAE norm. The cold cranking amperes according to the SAE norm is defined as the current that a fully charged battery can supply at a temperature of -17.8°C (0°F) for 30 seconds without the voltage dropping below 7.2 V. The higher the cold cranking amperes value, the better the starting capacity of the battery. In certain markets the batteries are marked according to the DIN norm.

Charging

The process by which a battery is supplied with energy by a charger or the generator (GEN) in the car. During charging, the lead sulfate in the plates is converted back to pure lead on the negative plates and to lead oxide on the positive plate. Water is consumed, sulfuric acid is formed and the density of the acid increases.

This reaction can be written

2 PbSO 4 + 2 H 2 O --> PbO 2 + Pb + 2 H 2 SO 4

The state of charge is expressed as the amount of electrical energy that is stored in the battery at any given time, in relation to how much energy can be stored in a fully charged battery. The state of charge is listed as a percentage of full charge. This is the "State of Charge", SOC.

Direct current, DC

An electrical current that only travels in one direction in an electrical cable. A battery supplies direct current during discharge and must be recharged (from the generator (GEN) or an external battery charger) with direct current in the opposite direction to current during discharge.

Plate

The plates in a battery function as electrodes. Each cells consists of several positive and negative plates. These plates are welded together in groups by plate straps. The plate is made up of a grid with an external layer of active material. This active material contributes to the electrochemical process during charging and discharging. The grid is constructed of a type of a lead alloy which functions as a conductor of the active material and also carries the current. The positive plate has an external layer of lead dioxide, while the external layer on the negative plate consists of porous lead.

SAE

An industry norm. SAE is an abbreviation of "Society of Automotive Engineers".

See Separator .

Self-discharge

A battery that is not in use will discharge itself over time. This is know as self-discharge and is quicker in hot environments. The battery must be maintained by recharging at regular intervals to avoid excessive discharge.

Sulfation

Sulfation is where, in some circumstances, large insoluble lead sulfate crystals are formed on the plates as the battery discharges. This reduces the capacity of the battery. Note that the formation of small soluble lead sulfate crystals is normal during discharge.

The plates always expand during discharge. If the discharge is very slow, the expansion may be so great that the plates deform or crack. Such damage is permanent and the battery must be discarded. This is an excessive form of sulfation. The longer the sulfation process continues, the more difficult it is to save the battery.

Sulfation is a result of a battery being left standing for a long period at a low charge, or the battery has been under charged repeatedly. Regular charging of the battery will prevent sulfation.

Acid density

The unit showing the amount of sulfuric acid in the electrolyte and is a measurement of the battery voltage and charge status. The density of the acid is measured in g/cm 3 . The higher the value of the acid density (i. e. high concentration of sulfuric acid), the higher the voltage and state of charge. A low acid density value means a correspondingly low concentration of sulfuric acid, low voltage and a reduced capability for providing current. The electrolyte in a fully charged battery has a density of 1.28 g/cm 3 . The density of the electrolyte in a fully discharged battery is 1.10 g/cm 3 .

HINT: For maintenance-free as well as sealed batteries (AGM) the battery acid cannot be accessed and thus its density cannot be measured.

Discharge

The process where a battery is under load and gives off current. During discharge, the lead on the negative plate and the lead oxide on the positive plate are converted to lead sulfate. Sulfuric acid is consumed and water is formed, reducing the density of the acid.

This reaction can be written

PbO 2 + Pb + 2 H 2 SO 4 --> 2 PbSO 4 + 2 H 2 O

Stand-by voltage

The stand-by voltage is the voltage measured from an unloaded battery after approximately 2 hours discharging or charging. It is important that the battery is left unloaded for a longer period so that the concentration of sulfuric acid has time to distribute evenly in the electrolyte. The measured voltage is then a good indication of the charge status of the battery.

Stand by current consumption

The stand by current is the current used by the car when the key is removed (such as the current for the clock, anti-theft alarm and remote control locking).

Volt (V)

Unit for electrical power. Abbreviated to V.

Volvo Battery Analyzer 3100

A tool used to test and troubleshoot batteries of open type.

Note. Not intended for AGM-batteries.

Surface charging

The concentration of sulfuric acid is higher at the plates than in the electrolyte in a battery that has recently been charged. This is because the sulfuric acid formed at the plates during charging has not had time to spread into the rest of the electrolyte. If the stand-by voltage of the battery is measured directly after charging, a higher value will be obtained, giving an incorrect reading of the charge status of the battery. This is called surface charging. If the battery is left without load for a while the concentration of the sulfuric acid will even out. It is therefore important to leave the battery without load for at least 2 hours before measuring the stand-by voltage of the battery, allowing time for the concentration of the sulfuric acid to even out in the electrolyte. The measured voltage is then a good indication of the charge status of the battery.

Scheme 28

ABS system diagram

Bosch 5.3 system (1) is extremely compact, which reduces the number of external components to a minimum. These components include only wheel sensors, ABS warning light, and brake light switch.

EBD is integrated in the ABS control module, but has a micro-processor of its own.

Input signals

Front (6) and rear (5) wheel speed sensors send these measurements to ABS-CM to determine if a wheel is about to be blocked.

The brake light switch (7) indicates to the control module that the brakes are being affected. This puts the control module in a high state of readiness for monitoring the wheels' speed.

Output signals

The ABS warning light (2) warns the driver about malfunctions occurring in the ABS-system, which has resulted in automatic shutdown of the system.

In addition to warning for low brake fluid level, the brake fluid warning light (3) warns the driver about malfunctions in the EBD-system. This is independent of the ABS circuit. The EBD-warning is needed to warn the driver that the car may have poorer stability during braking.

DLC (4) is used to connect the diagnostics tool.

Other 'output signals' are used internally. These switch the pump relay and the relay for feed to inlet and outlet valves. The valves are controlled by then being grounded in the electrical control module. Valves and the motor are located in the hydraulic part of the ABS-unit.

Other output signals

If the car is equipped with DSA, this control module must know the wheels' speed to measure wheel spin. This information is received by the DSA control module from the ABS control module. Four communication lines are available for this purpose.

The DSA control module has no interaction or effect at all on ABS.

The combination instrument receives the wheel speed signal from right/front ABS sensor for the car's speed and driving distance.

Self-test

When the ignition is turned on, the system checks all components for their resistance values. During this check the control light is lit. The light goes off after the check (4 seconds).

When the car starts to roll with a speed of approx. 4 km/h (2.5 mph) the pump motor is checked (and the relay). The inlet and outlet valves will also be powered up briefly.

At a speed of approx. 65 km/h (25 mph), the wheel sensors' function will be checked.

If a malfunction is detected in the system, the light stays on constantly. Troubleshooting can be done with the diagnostics tool.

The ABS system works at speeds above 4 km/h (2.5 mph).

DSA (dynamic stabilizing system) controls engine power to help to prevent the driving wheels from spinning too much. This system has nothing in common with the TRACS-system used for other Volvo models. TRACS brakes the spinning wheel to slow it down. The DSA system only uses the wheel speed information from the ABS control module.

Scheme 29

Brake caliper

The front brake discs are ventilated and the front brake calipers have cooling fins to ensure optimal temperature.

Lucas brake calipers are of the floating type with a single piston. This design makes it very easy to change brake pads. The brake pads can be accessed after the brake caliper's floating part has been tilted up over the upper guide pin.

Wear indicator

The brake pads feature a wear indicator. This small metal clip is fastened on the brake pad's backing plate. When the brake pad has been worn down so much that it has to be changed the free end of the plate will have contact with the brake disc, which causes a squeaking noise. The indicator's free end has a length of 2 mm (approx. 1/12 in).

The indicator does not cause any extra wear of the brake disc.

Specification front wheel brakes

The wear indicator is delivered together with bolts and Loctite R in the brake pad kit. They must be placed in correct position to work as intended.

Even with wear indicator, the brake pads (and discs) should be checked at every service.

Scheme 30

Divided brake system

The two-circuit brake system is also separated in the hydraulic unit. For this purpose the pump has two pistons. When ABS is active each piston supplies pressure to one of the two brake circuits, that is, primary and secondary brake circuits. The pump is driven by an electric motor.

For each brake circuit the system has two inlet and outlet valves. The inlet valve is a valve that normally is open while the outlet valve is a non-return valve that normally is closed. This makes it possible for the brake system to work conventionally when the brakes are affected.

The system has a low-choice control of the rear wheel brakes. This means that the brake pressure on the rear wheel brakes is mutually even and is adapted to the most critical wheel.

The rear wheels' brake circuit has no pressure reducing valves. The lower pressure that is needed is controlled by the EBD-system.

Functions

There are three situations

1. keep the pressure by closing the inlet valve. The outlet valve is not supplied with current and thus remains closed.
2. lower the pressure by opening the outlet valve. Therefore both valves, inlet and outlet, are supplied with current.
3. build up pressure again by opening the inlet valve, at the same time as the outlet valve is closed. None of the valves are supplied with more current and return to the start position. The pump remains connected and builds up pressure in the wheel brake cylinder.

The pump is driven constantly during ABS-activation. The inlet and outlet valves control the brake pressure in the brake cylinders.

The pump is not operated when EBD is activated. The pressure in the rear brake calipers is controlled by the valves.

When ABS is activated the brake fluid circulates in the hydraulic unit's high-pressure part and is not directed back to the reservoir.

Buffer compartments

Buffer compartments' functions (S)

1. When the outlet valve opens the pressure in the wheel cylinder must be lowered very quickly. The purpose of the buffer compartments is to catch the fluid, especially if the pump has not yet reached full RPM. It is a small compartment that holds approx. 2 cm 3 with a weak spring and piston. The high pressure can now be unloaded as the fluid can be pressed into the compartment.
2. The weak spring behind the piston helps the pump start if it starts before the outlet valve opens.

Buffer compartments' function (D)

1. These buffer compartments have the purpose of absorbing the pressure variations in the system caused by the piston pump. This helps to reduce the sound level in the system.

Scheme 31

The parking brake applies the brake pads directly against the rear discs. There is no internal drum. Therefore the rear brake calipers have an integrated parking brake mechanism.

The mechanism adjusts itself after every time the brake is used.

The parking brake cable's horizontal movement is converted to a rotating movement at the input shaft (1). At the end of the shaft there is a plate (2) with three tapered recesses (3). There is a ball bearing in each recess. Together with the sealing plate (4) this unit forms a bearing with 3 balls, which means that the shaft (1) is displaced axially when it is turned. To start with, the axial displacement is big in relation to the rotation and then gets smaller in relation to the rotation. This results in an increase of the application force.

When the parking brake is applied, the shaft (1) is rotated and displaced axially. This means that the setting shaft (5) moves against a spring pressure (6). This shaft absorbs the movement via the nut (7) for the wheel brake's piston (8).

This forces the piston against the brake pad. Thanks to the floating brake caliper, the brake disc is locked by both brake pads.

The setting shaft (6) has threads with high pitch which means that the nut (8) is threaded up. In this way, a new setting is made every time the brake is applied.

After a brake application, the seal ring (9) will force back the piston slightly. The piston can perform this movement since there is a small play in the screw's thread.

When changing brake pads, the setting shaft must be turned back by rotating the brake piston with the special tool.

Adjusting parking brake cable

The parking brake's cable is adjusted by the parking brake lever. The adjusting nut (10) is accessed from inside the passenger compartment. The balancing yoke (11) is needed to distribute the brake force evenly to both rear wheels. You can also access this from inside the passenger compartment.

Rear wheel brakes

Brake caliper

The rear brake discs are not ventilated. The brake calipers are located behind the axle.

The brake calipers are also of the floating type with one cylinder.

Special tools

When new brake pads are installed on the rear, special tool 999-5634 shall be used to turn back the brake piston.

Specification rear wheel brakes

Summary of the brake system

S40/V40 features a diagonally divided brake system with disc brakes on all 4 wheels.

1. The master cylinder's primary section supplies the left front and right rear.
2. The master cylinder's secondary section supplies the right front and left rear.

Bosch 5.3 ABS with EBD is standard on S40/V40.

It is a closed system, since there is no return line from the ABS-unit back to brake fluid reservoir.

The system's electronic and hydraulic parts are integrated into one unit. However, service can be performed separately on them.

It is an extremely compact and reliable installation. There is no longer any cabling between the two parts. The whole unit is installed on the right side of the fender liner in the engine compartment, in front of the strut.

Due to the diagonally divided system, the hydraulic modulator has an output for each wheel.

The ABS brake system has a conventional tandem master cylinder with vacuum-assisted power brakes.

The brake fluid reservoir is installed on the brake's master cylinder and contains a float to indicate the fluid level. Level warning is generated if the fluid level is lower than the min. marking.

Scheme 32

Central electronic module (CEM) controls many functions to improve quality and comfort. Central electronic module (CEM) can combine functions and relate functions to physical conditions. Functions of the Central electronic module (CEM) can be divided into the groups Lighting and Wiper functions.

Note. This Central electronic module (CEM) is not part of a CAN-network.

Headlamps

Since twin headlights are used, the low beams are also on when the high beams are on. DRL (running lights) or NDRL (normal headlights) can be programmed by the customer and with diagnostics tool.

DRL= Daytime Running Light, NDRL= Non Daytime Running Light

1. By the customer: The light switch must be in position for parking lights. The ignition must be on (pos. II). Hold and turn the light switch towards yourself and turn the headlight switch to pos. 0. The green light-emitting diode below the switch is lit to confirm that DRL is on. To return to NDRL, do the same thing and the green light-emitting diode goes off as confirmation.
2. Witt the diagnostics tool; follow the instructions in the program menu.

If DRL is programmed

1. Continuous high beams in key position 2.
2. High beams only in key position 2.
3. Flash the light with a light pull.
4. Continuous light with a heavy pull.

Some functions must be programmed in Central electronic module (CEM) after the module has been replaced

1. Since twin headlights are installed, high beams and low beams can be on at the same time
2. Running lights
3. Rear wiper for V40
4. Follow-Me-Home lighting

Switches have a smoother design thanks to lower current flow through these switches.

If a switch is activated for a longer time than 180 seconds (e. g., if it jams), the function is shut off for safety reasons.

When the starter motor is engaged (key in pos. 3), all functions are cancelled without the functions' status changing.

If voltage is too low and high beams are selected, only low beams are available.

Should a major malfunction occur on Central electronic module (CEM), the low beams are turned on.

Wash/wipe

If rear window washing is used for shorter time than 350 ms, a wiper stroke (impulse function) is performed, which cancels the interval function.

For rear window wiper, the wiper performs three strokes after washing. The windshield wipers perform two strokes, followed by an extra stroke.

Washer functions front and rear are not synchronized.

The rear window washer is activated when reversing if the windshield wiper is engaged and reverse gear is selected. The rear window wiper does not have to be activated.

Lighting

Central electronic module (CEM) controls the following functions itself and reads off status of the other functions that are controlled directly by the lever

1. 0 windshield wiper
2. interval wiper windshield
3. 0 rear window wiper
4. interval wiper rear window

Fog lamps

Fog lights front can only be turned on when the key is in pos. 2 and light switch in pos. 1 or 2.

Rear fog lights can be turned on with the key in pos. 2 and light switch in pos. 2, or light switch is in pos. 1 and front fog lights are on.

All fog lights are turned off when the light switch is set in pos. 0, or the ignition is turned off.

If fog lights have been installed as accessories, a new push-button has to be installed on the light switch. The fog light must be programmed with the diagnostics tool.

"Follow-Me-Home"

If you pull on the light lever with the key in pos. 0 or 1, the low beams are lit for 30 seconds.

If another light pull is performed during this 30 second period, the low beams go off.

"Follow-Me-Home"-function can be programmed (activated/deactivated with the diagnostics tool).

Tail lights and parking lights

For safety reasons, the lighting is divided into two separate circuits.

1. The parking circuit includes the outer tail lights and parking lights in the headlights.
2. The tail light circuit includes the front and rear side running lights, the inner tail lights, and license plate lighting.

The parking lights are on if the light switch is in pos. 1 and the key is in pos. 0 or 1.

With key in pos. 0 or 1, the tail lights are off and the parking lights on only if the light switch is in pos. 1.

The right lever has four functions for washing/wiping in S40, and six functions in V40 (rear window washer/wiper).

1. up function: impulse
2. off function: 0
3. three down: interval, speed 1, speed 2
4. pull: wash windshield

In V40

1. shift: rear wiper
2. press: washer rear

Interval time

The interval's duration for the windshield wipers (and rear wiper due to the synchronization function) varies with the speed of the car.

Rheostat

The rheostat can control the light intensity in 16 steps, with a 12% to 100% activation cycle.

If the key is in position 2, the rheostat controls the light intensity of the instrument lighting in the passenger compartment.

1. combination instrument
2. heater instrument
3. radio

Central electronic module (CEM) reads off the thumb wheel's status (resistance) which is located beside the light switch, which then controls the light with an activation cycle.

Rear window wiper

The rear window wiper is synchronized with the windshield wipers. It wipes at every other stroke of the windshield wipers if they are controlled by interval wiping. If the windshield wipers are activated continuously the rear window wiper's interval is twice as long as in the above table.

If the windshield wipers are activated (continuously or interval) and reverse gear is engaged, the rear window wiper is automatically activated for two strokes.

An impulse function can be started by briefly activating the washer function.

Washing

Both rear window and windshield washers work in three phases.

1. Prewash: the pump is activated for a certain time and the wipers remain in the parking position
2. Washing: the pump and wipers are active for as long as the washer switch is actuated
3. After washing; the pump is off and the wipers are active for at least two complete strokes, with an extra stroke three seconds later.

With the lever in position 0 and washer function requested, three phases follow.

If speeds 1, 2, or impulse is active and the washer function is requested, the washer pump is engaged for as long as the switch is active. Return takes place to speeds 1, 2, or impulse.

If interval wiping is active when the washer function is requested, then interval wiping is interrupted and the three phases start. After the three phases have been finished interval wiping resumes.

Glow plug monitor

When the key is in positions 2 or 3, the Central electronic module (CEM) controls the brake lights with regards to any problems.

The control light in the combination instrument lights up for 3 seconds and goes off even if the brake is not applied. Should a problem occur, the control lights light up and stay on when the brake is applied.

Scheme 33

AC installation in the car

The air conditioning used in this car is a conventional installation where a thermostat-controlled expansion valve (TEV/TXV) works as control valve.

The expansion valve controls the amount of refrigerant that passes the evaporator. The quantity depends on the temperature in the evaporator's outlet pipe. If the temperature is too low the amount is reduced slightly by closing the valve. When the temperature increases, the valve opens slightly again to let in more fluid in the evaporator. In this way, a balanced state is achieved.

The filler nipple is located against the engine compartment wall in the high-pressure line.

The AC-system is filled with environment-friendly R134a refrigerant, just like all other Volvo cars.

The system has two filler nipples. One in the high-pressure circuit for the evaporator, and one in the low-pressure after the evaporator.

Scheme 34

Extra air can be taken directly from the evaporator and in to the passenger compartment through the middle vent on the instrument panel. The more the control is turned towards the blue marking, the more cold air will be mixed in with the temperature-controlled air. This function works in the same way as for S70/V70/C70.

HINT: If the heating coil is not used (no airflow through the heating coil), there is no noticeable temperature-difference when the air mixer is open and when it is closed. You can only perceive an air mixture if the ambient temperature is lower than 6-8 °C (43-46 °F).

Scheme 35

The control panel and all switches that belong to climate control are located on the middle of the instrument panel. Three large rotary controls control fan speed, air distribution, and temperature. There are also three switches that control recirculation, electrically heated rear window, and activation of AC system (AUTO or OFF).

This system allows a mixture of passenger compartment air and fresh air through the middle air vents. For more information about this "air mix function", see: Air mixing openings

The airflow's direction can be adjusted individually for all vents on the instrument panel.

The recirculation button to the left on the control panel controls the two valves that close the fresh air inlet. This connects heater/ventilation unit with the interior. At recirculation, the air is recirculated to 100%.

The two recirculation valves only have two positions - fully open or fully closed.

The rear window's heating works via contact +15. This means that the rear window's electric heat is connected even if the engine is not running.

No time-controlled RECIRC-function.

Scheme 36

ECC control panel is located directly on the control module.

The passenger compartment temperature sensor is an NTC-resistor located behind the left grill directly beside the recirculation button. The passenger compartment air is taken in through this grill. For this reason there is an extra venturi in the channel to the heater. The vacuum that is created by this venturi sucks air out of the passenger compartment along the temperature sensor. The control module calculates the difference between measured air temperature and set temperature.

Other input signals - received directly from the control panel

1. Passenger compartment temperature sensor
2. Temperature setting control
3. Rotary control for air distribution
4. Fan control
5. AC selector
6. Recirculation button

The alternator's charging signal is a signal that establishes if the engine is running. It is used for the fan. If the engine is not running but the ignition is on, the fan will not be run if AUTO has been selected. This is to prevent the battery from being drained.

Additional conditions for engaging the compressor

Engine control module (ECM) will not transmit an incoming request if

1. coolant temperature is above 125 °C (257 °F)
2. pressure in AC system is lower than 200 kPa (29 psi) or higher than 3000 kPa (435 psi).
3. full throttle (WOT) is applied (for 10 seconds)

If the Engine control module (ECM) fulfills the AC request, it sends a signal to the compressor (8) via a relay.

Scheme 37

Several openings can be used

1. 14 defroster openings - leads air to the windshield and the front doors' windows for fast warm-up and demisting. The air can pass through the evaporator and the heater.
2. 4 ventilation openings - blows in air directly to the passenger compartment. Vents can be set in different directions and can be closed individually.
3. 6 floor vents - are located on both sides of the center console and blow out air both front and back.
4. Air mix openings - the two middle openings are also used for the air mix function. Non-warmed air can be directed to these openings. For more information, see: «Air mixing openings»(ref-441295-S17902844362011121500000)

Structure in the car

The heating system and air conditioning unit in the car are built up of three separate parts.

A.

This unit is the air inlet. The fan motor and recirculation valves are also located there. The recirculation valves are electrically operated by a servo motor. They only have two positions: fully open or fully closed. Closed means 100% recirculation. This can be set manually or with the ECC control module.

B.

The evaporator is located in this unit. The temperature sensors for the ECC-system and AC-system's temperature-controlled expansion valve are located directly on top of the evaporator. The pollen filter is located in front of the evaporator.

C.

This is the location of the heating coil, valves for air distribution to the various vents, and the valve for air mix.

Scheme 38

Rotary controls

Left rotary control is used to control fan speed. The following alternatives are available

1. AUTO-function
2. Off (ECC is turned off)
3. Five different fan speeds (in these positions the automatic setting is disabled).

In AUTO, ECC will select the best fan speed to reach the desired temperature. The fan speed is variable and has 100 steps. The different speeds are controlled electronically.

If AUTO has been selected, fan speed is dependent on

1. set temperature
2. current temperature
3. car's speed
4. coolant temperature.

The rotary control in the middle is used for air distribution. In AUTO, ECC selects the most effective air distribution to reach set temperature as fast as possible. If DEFROST is selected the AC is always turned on automatically and the fan starts with the highest speed. This rotary control can be turned 360°. Servo motors act on the dampers that are responsible for air distribution. These servo motors are connected directly to the ECC control module, which can read off their respective positions via feedback potentiometers. The damper RECIRC does not send back information since it is only open or closed.

Right rotary control is used to set desired passenger compartment temperature in °C (°F). To reach this temperature the AC button has to be set to Auto and the fan must be set to at least position 1 or AUT. If the red or blue marking is selected (highest or lowest temperature), the fan motor will start at the highest speed.

Switches

The recirculation button controls the recirculation dampers. They can be opened or closed, there are no intermediate positions. The dampers can also be controlled by the ECC control module.

The electrically heated rear window can be turned on together with heating of the outside mirrors using the button in the middle.

Position AUTO; ECC control module controls AC by sending a request to Engine control module (ECM) depending on different conditions. The AC compressor is controlled by Engine control module (ECM).

Position OFF; AC is off, but will be turned on if DEFROST is selected.

Note. The passenger compartment's temperature sensor is located behind the left ventilation grill. As long as the fan is on air will flow through this grill to ensure the sensor's function. Do not place decals, etc. over this grill. Then the ECC cannot control the temperature

General

Factors that have improved safety, increased comfort, added functions and increased environmental friendliness, have made modern vehicles more and more complicated.

The more complicated the vehicle is, the more important is the diagnostics system in the vehicle with the diagnostics tool when it comes to ensuring fast, safe and economic test, service and repair.

To reduce emissions from the vehicle, the diagnostic systems shall also, according to legislation, detect emission-influencing problems as well as defects that may cause follow-up damage on emission-related components.

Legal requirements emissions

OBD I - On Board Diagnostic I

On Board Diagnostic I (diagnostic system in the vehicle) was 1988 a requirement from CARB (California Air Resource Board) which is an air quality board. The purpose of these regulations was to ensure that component or function defects that affected exhaust emissions are detected by the control module's diagnostic functions.

OBD I included diagnosis of control module, emission-related components connected to the control module as well as exhaust gas recirculation.

Using the diagnostic socket in the engine compartment, the information about the system was accessible to all, both brand-name workshops and independent workshops.

In case of a detected emission-related problem, a warning light is activated in the driver information module (MIL= Malfunction Indicator Light), when the problem is confirmed as a real malfunction. Thus, the light is not activated immediately upon detection, only first when the malfunction is confirmed, which may be, e. g., following a few driving cycles.

OBD II - On Board Diagnostic II

Scheme 39

On Board Diagnostic II was another requirement from CARB that applied from 1996. CARB demanded additional and refined diagnosis for emission-related component and systems in the drivetrain (engine and transmission).

Also, a standardized communication method was required for reading out of diagnosis (Standard SAE J1979 and J2190, where J2190 is voluntary and includes Enhanced Diagnostics - the vehicle manufacturer's own diagnosis in addition to legal requirements).

It should be possible to read out diagnostic trouble codes and their format, information connected to diagnostic trouble codes as well as parameters*, according to this standard. OBD II's diagnostic trouble codes are five-digit and begin with the letter P followed by four digits.

This standardized communication method means that anyone shall be able to manufacture and sell an instrument for reading out, a so-called Generic Scan Tool. Thus, the vehicle owner is not dependent on using a brand-name workshop.

The standard OBD II requires a standardized diagnostic socket in the passenger compartment near the driver's seat, where this instrument is to be plugged in. This means that the diagnostic socket (connector) is the same on all vehicles regardless of manufacturer or model.

However, there is a difference between manufacturers regarding which pins are used in the connector. This depends on the OBD II standard supports four types of communication protocols.

A protocol may be said to be the "language" that is to be used for communication with the control module.

Scheme 40

Standardized pins on OBD II-connector

1. Pin 2 SAE J-1850 bus +
2. Pin 4 Chassis ground
3. Pin 5 Signal ground
4. Pin 6 SAE J-2284, CAN-bus (CAN-H)
5. Pin 7 SAE J1979, ISO 9141-2 / ISO14230-4, K-line
6. Pin 10 SAE J-1850 bus
7. Pin 14 SAE J.2284, CAN-bus (CAN-L)
8. Pin 15 ISO 9141-2 / ISO14230-4, L-line
9. Pin 16 Voltage feed

Other pins in the connector are permitted for the vehicle manufacturer's own specific use. On pin 7 (K-line), two-way communication is permitted, on pin 15 (L-line) only one-way communication is permitted to the control module. Therefore, the L-line is missing in many vehicles.

ISO14230-4 = Protocol KWP2000.

OBD II was first introduced for Volvo on engine management system Motronic 4.3, Motronic 4.4, and automatic transmission AW 50 42, AW 30 40/43 in model 850/960 for market USA/CDN.

With time, OBD II-communication with control modules via CAN is introduced.

The legal requirement also includes the function Readiness Monitoring, see other section.

* Parameter refers to, e. g., RPM, engine temperature, battery voltage, etc., with associated value 800 RPM, 87 °C as well as 14,2 V, etc.

EOBD - European On Board Diagnostic

EOBD, European On Board Diagnostic is a legal requirement in Europe which, in principle, includes the same requirements as OBD II. EOBD applies to spark plug engines (gasoline engines) registered year 2000 and later, and self-igniting engines (diesel engines) registered 2003 and later.

For information about, among other diagnostic socket, see OBD II above.

Since the end of the 1980s, the control module's diagnosis has developed from detecting simple problems and storing a small amount of information to including more complicated tests and checks.

Today a large amount of information can be read out both about the detected problem as well as parameters from the control module's input and output signals.

The following accounts for the main principles for this development.

Scheme 41

A Volvo standard was introduced (Volvo Diagnostics I) 1988 , which means diagnosis of several on-board systems (On Board Diagnostic).

This Volvo Diagnostics included

1. Store problem indicators (diagnostic trouble codes) for various components as well as delete them (check function 1).
2. Confirmation of activating components or functions (check function 2).
3. Cyclic activation of components/functions (check function 3).

A diagnostic tool (diagnostic socket with light-emitting diode) was located in the engine compartment for reading out a Volvo Diagnosis from the various control modules.

Volvo Diagnostics, the first version is found on, e. g., fuel control system LH 2.4 and ignition system EZ 116K for model 240 and 740.

Non-standardized serial communication

As a supplement to Volvo Diagnostics - first and second version, the supplier of engine management systems developed their own diagnostic and communication methods (On Board Diagnostic). These were introduced during 1991/92 .

These serial* communication methods were supplier-specific and varied a lot between systems. To communicate quickly and directly with control modules was a pre-condition for developing the control system and opened for new possibilities.

The access to more information about the detected problem as well as the possibility to, e. g., quickly read out parameters, enabled improvement of troubleshooting methods. Therefore, these communication methods were used by the workshops' diagnostics tools.

The cable in the vehicle used for this serial communication is connected to the diagnostic socket in the engine compartment and is the same one used for Volvo Diagnostics, first and second version.

Included functions are, among others

1. Reading out and erasing diagnostic trouble codes.
2. Reading off frozen values.
3. Reading off values of signals such as coolant temperature, voltage on heated oxygen sensor, etc.
4. Activating components and functions.
5. Programming of customer parameters and functions.
6. Calibration of functions.
7. Resetting of adaptations.

The tool Volvo System Tester was developed to make communication easier with the control module.

Non-standardized serial communication was introduced on engine management system Motronic 1.8 in model 960 and engine management system Fenix 5.2, Motronic 4.3, and LH3.2/EZ129K in model 850.

* Serial means that the information is sent as a series of signals in the form pulse trains (= series of pulses) via a cable between the tool and control module.

Parameters

Parameters or values are data that are read out from the control module's memory positions to, e. g., check the signal from a sensor or identify the control module's software version.

In principle, parameters can be divided into two parts

1. one for dynamic values continuously updated in the control module
2. one for static values not changed by the control module and always stored.

Parameters, dynamic

Scheme 42

The dynamic values are stored in the control module's RAM-memory, which means that the values disappear when the memory's power supply is turned off (control module is turned off). As soon as the control module's power is turned on (ignition on), values are stored again.

Example of values are

1. Outside temperature
2. Engine speed
3. Load
4. Coolant temperature
5. Vehicle speed
6. Battery voltage

Values are updated continuously after a pre-determined time interval. This means that certain values are updated with very short time interval, while other values are updated more seldom. Update rate is determined by how important the value is to the control module.

By reading off the value from, e. g., a sensor or switch, it can be decided if the signal is correct or not.

Note. When a malfunction is detected and a diagnostic trouble code is stored, it may well be that the displayed value is a replacement value and not the real value. If the value does not change, e. g., if the sensor is disconnected, it may be the replacement value that is shown.

Parameters, static

Scheme 43

The static values are stored in the control module's EEPROM, which means that these values are always stored regardless of if the control module is on or off. These values are normally not updated by the control module, instead they are only changed using, e. g., the diagnostics tool at vehicle manufacture in the factory or reprogramming during a workshop visit.

Example of values are

1. Hardware P/N (control module without software).
2. Hardware serial number (control module without software).
3. Software P/N.
4. Diagnostic software P/N.
5. Customer-programmed values, e. g., passenger compartment temperature, alarm on and off.
6. The vehicle's configuration, that is, the vehicle's content and equipment that can be used to compare the vehicle's equipment physically with how the vehicle is configured. The configuration may be affected/changed, e. g., when downloading software.

Scheme 44

Wit this service it is possible to trigger (activate) the components that are connected to the control module. Examples of components are

1. Relays
2. Solenoids
3. Lock motors
4. Damper motors
5. Signals to other control modules.

Note. If a malfunction is detected, diagnostic trouble code is stored and emergency functions or modes, etc. are activated to "protect" the system, the control module can prevent activation.

Depending on the system, the control module or diagnostics tool can perform activations in different ways, for some the component is activated according to a certain pattern, e. g., OFF, ON, OFF, ON, OF, ON, etc. in a sequence.

For other systems, the component is activated, e. g., ON, and remain on until the activation is stopped.

Software downloading

New software can be downloaded to the control modules. When ordering software the vehicle software and hardware are compared to Volvo's central database. If the comparison corresponds the new software is downloaded to the control module.

If the comparison between the car and Volvo's central database does not correspond, then the database is updated with the vehicle's configuration. When this is complete the software is downloaded.

For further information regarding downloading, see Design and Function, Downloading Software.

Readiness Monitor (certain markets only)

This is a function in Engine control module (ECM) that controls the control module's emission-related sub-system. With the function you can read out if the control module has run all diagnostics for the following sub-systems

1. Misfiring
2. Fuel system
3. Catalytic converter
4. Evaporative emission (EVAP) system
5. Heated oxygen sensors (HO2S)
6. Other related components

Thus, Readiness refers only to if the diagnostics (tests) have been run or not, not if a malfunction was found or not. If a malfunction is found during the test, a diagnostic trouble code is stored and the malfunction light (MIL-light) is lit.

If the tests are run in the driving cycle without detecting a malfunction, then "Readiness" is immediately generated to OK.

However, if a malfunction is found in the driving cycle, then Readiness is generated to Not Ok, and another driving cycle is required where the test is run to generate Readiness to Ok.

The following alternatives are possible

1. Readiness is run (Ok), no malfunction detected, which means that the vehicle can be approved in a check.
2. Readiness is run (Ok), with malfunction detected, which means that the vehicle cannot be approved in a check.
3. Readiness is not run (Not ok), which means that the vehicle cannot be approved in a check.

Readiness was originally a requirement from the American authority, United States Environmental Protection Agency (EPA), and is used there for Inspection and maintenance test (IM-test) (corresponds to annual inspection). Depending on legal requirements, the function may also be found on other markets.

Scheme 45

All control modules' diagnostics require that some form of driving cycle or operation cycle is run for diagnostics to be considered as complete. The terms driving cycle or operation cycle appear, these mean the same, they are only different designations.

Example

The illustration above shows an example of a driving cycle or operation cycle. The vehicle is started and driven (Start) , is stopped sometime and the ignition is turned off (Stop) . When the ignition is turned on again (Start) a new driving cycle starts.

A new driving cycle or operation cycle usually starts every time the ignition is turned on, which means that you should turn on the ignition, turn off the ignition, and then turn on the ignition again.

However, the condition varies from control module to control module, there are also, e. g., speed and temperature conditions, before a driving cycle or operation cycle is considered to be complete.

When a malfunction is detected and then is confirmed as a real malfunction and is stored, various counters are also stored, indicating how frequent the malfunction is. These counters use driving cycles or operation cycles as basis for updating the counters' values.

For information on counters, see further on in the document.

Frozen values

For every diagnostic trouble code, pre-defined parameters are frozen and stored in the control module. The frozen values are stored immediately after the malfunction has been detected and gives a "picture" of the conditions when the malfunction was stored.

Note. Status identifier, Counter and Frozen values are the most important factors to deciding the malfunction's nature, that is, to decide

1. when the malfunction was detected (frozen values, counters)
2. what the driving conditions were at the time (frozen values)
3. status for the test (self-diagnosis) (status identifier)
4. how frequent the malfunction is (counter).

In newer car models, frozen values consist of a number of global (common) general parameters as well as a number of control model-unique parameters. Global may be

1. Road distance
2. Battery voltage
3. Passenger compartment temperature
4. Outside temperature
5. Engine running

In addition to these, the diagnostic trouble code-unique parameters are stored which are especially selected parameters for the diagnostic trouble code.

Most parameters in the frozen values are the same for all malfunctions and indicate a general condition when a malfunction was detected, for example

1. Road distance
2. Outside temperature
3. Engine speed
4. Load
5. Coolant temperature
6. Vehicle speed
7. Battery voltage
8. etc.

Some of them have been selected to give a better understanding of the specific malfunction.

Note. When erasing diagnostic trouble codes, stored frozen values are also erased.

HINT: Reading out and interpreting these frozen values make it easier to understand when in time the malfunction occurred, as well as under what driving and environment conditions the malfunction was detected, related to when and how the customer experienced the symptom.

Emergency mode, back-up mode "Limp-home"

When a malfunction has occurred in the system that is confirmed (permanent malfunction) and is registered by the control module, modes are activated for certain systems and functions to handle the malfunction.

The purpose of these actions is to "protect" the control system and at the same time retain as much functionality or driving function as possible.

The minor malfunctions do not activate any back-up modes, there are different programs depending on type of malfunction and which control system to which it applies. All control systems do not have emergency modes or back-up modes.

Sometimes emergency modes must be activated immediately when a malfunction is detected, even if there has been no time to confirm and store any diagnostic trouble code. This is to maintain certain function, e. g., in case of malfunction of the mass air floe sensor for the engine management system, when the emergency program tries to prevent the engine from stopping.

HINT: Limp-home, emergency mode or back-up mode that may appear in case of malfunction is described in diagnostic trouble code information under replacement values.

For, e. g., automatic transmission TF-80SC AWD (XC90, B8444S) there are two back-up modes

1. Failsafe action (temporary action)
2. Emergency/limp-home mode

Failsafe action is activated at the first detection of the malfunction, if the malfunction disappears the system returns to normal function.

Emergency mode is activated in case of less serious malfunctions Limp-home mode is activated for the most serious malfunctions.

The warning light in the driver information module lights up, and a text message is shown in the text window in the driver information module that emergency/limp-home mode has been activated. When the ignition is turned off and on again, no text is shown until the malfunction is detected again.

Note. If the malfunction disappears (intermittent malfunction) the control module returns to normal function first when the ignition is turned on the next time.

For automatic transmission's emergency mode, the following may take place, e. g.

1. Adaptation function is blocked.
2. Lock-up function is blocked.
3. Function slipping lock-up is blocked.
4. Function neutral check is blocked.
5. The transmission only shifts to 3rd gear and reverse gear. All other shifting is blocked.

The above actions will be noticed by the driver since only one gear can be sued. Some may also notice that lock-up is not engaged. Then the vehicle comes to the workshop with a symptom for some form of lost driving function, probably also with the warning light on.

This symptom shall not be confused with the malfunction itself, instead it is a symptom of the back-up mode. The symptom that the malfunction itself causes (it it causes any) may be noticed briefly or not at all.

Note. If the malfunction is confirmed (permanent) it may be that the control module resumes normal function at ignition off and on again (symptom does not exist any longer). First when the malfunction is detected again (diagnostic trouble code test started and conditions fulfilled), the back-up mode is activated. The malfunction may then first be interpreted as if it was intermittent (non-existent or not active).

List Of Control Module Counters

For every diagnostic trouble code , the control modules stores a number of counters. These counters count the number of driving cycles that have been performed in the control module with or without malfunctions, if the malfunction is detected or not. In control systems older than model year 1999, there may be control systems, depending on control system, without counters or with few counters. From model year 1999, there are systems with several counters. The following counters may appear

1. Counter 1
2. Counter 2 *
3. Counter 3
4. Counter 4
5. Counter 5**
6. Counter 6
7. Counter 7
8. Counter 8

The text uses the term driving cycle, which may also be called Operation cycle.

In principle, only systems with the diagnostic concept Generic Global Diagnostic (GGD).

*** Only for emission-related systems.

When erasing diagnostic trouble codes, the diagnostic trouble code's counter is erased.

Note. Status identifier, Counter and Frozen values are the most important factors to deciding the malfunction's nature, that is, to decide

1. when the malfunction was detected (frozen values, counters)
2. what the driving conditions were at the time (frozen values)
3. status for the test (self-diagnosis) (status identifier)
4. how frequent the malfunction is (counter).

Scheme 46

Graph A illustrates when in time that the malfunction occurs. In the illustration, the control module has detected a malfunction in the second driving cycle (graph's x-axis) and this malfunction then appears 4 more times, a total of 5 times. Counters can be read out for every diagnostic trouble code in the control module which have this introduced. Driving cycles are marked with vertical lines. A driving cycle often begins with ignition on and ends with ignition off.

Counter 1 (C#1). Counts number of cycles performed since the malfunction was confirmed last . As soon as a malfunction is detected and confirmed, the value is reset.

When the malfunction is both detected and disappears in the second driving cycle (graph A), counter 1 will count up to 1 first in the following driving cycle (driving cycle 3), that is, a driving cycle has been run through since the last time the malfunction was confirmed.

In driving cycle 4, the counter is updated again, now to value 2. Just after that, the malfunction is detected (graph A), the malfunction is confirmed and the counter's value is reset. This sequence is repeated once again in driving cycle 5.

With other words, one can say that if the value is zero, the malfunction exists now or has existed earlier in the current driving cycle. If the vehicle is restarted so that a new driving cycle is initiated (often requires ignition off and on again) in this position and the counter's value still is 0, then you probably have a permanent malfunction.

Values near zero indicate that the malfunction has been detected recently. It may also be that the malfunction exists but the diagnostic trouble code test has not started in these driving cycles, which means that the counter has not been reset. A high counter value indicates that the malfunction was last detected a number of driving cycles ago.

Counter 3 (C#3) (see graph). Counts the number of driving cycles performed since the malfunction was confirmed the first time. When a malfunction is confirmed the first time, the counter will count up by 1 for every subsequent driving cycle, regardless of if the malfunction is detected or not. Thus, the counter tracks the number of driving cycles since the malfunction was detected the first time. See graph where the counter increases by 1 for every subsequent driving cycle and the value of the counter is finally 6.

A low value indicates that the malfunction was detected for the first time relatively recently. However, a high value indicates that a first detection was performed some time ago.

Counter 4 (C#4) (see graph). Counts the number of driving cycles in which the malfunction has been confirmed since it was confirmed the first time. The graph shows that after the malfunction was detected the first time, the malfunction has been detected in 3 driving cycles. Thus, after the malfunction was detected the first time, another 6 driving cycles (counter 3), have passed and in these the malfunction has been detected 3 times (counter 3). Simplified, one can say that in this example, the malfunction has occurred/been detected in every other driving cycle, and the malfunction can be assessed as relatively frequent.

A certain indication of a malfunction's intensity can be obtained if you compare the value for counter 4 with counter 3. The closer the value for counter 4 the value is to the value of counter 3, the more frequent the malfunction.

If counters 3 and 4 have the same value, the malfunction has been detected in every driving cycle, which means that the malfunction is frequent.

Counter 5 (C#5). The counter sums up the time in seconds that the control module has been operating since the malfunction first was confirmed and the diagnostic trouble code was stored. The time that the control module has been operating is only counted when it is active, not in "sleep mode". The counter is not shown in the illustration.

Counter 6 (C#6). The counter sums up the time in seconds that the diagnostic trouble code test has been in progress since the malfunction first was confirmed and the diagnostic trouble code was stored. The counter is not shown in the illustration.

Counter 7 (C#7). The counter sums up the time in seconds that malfunction has been confirmed since it first was confirmed and the diagnostic trouble code was stored. The counter is not shown in the illustration.

Scheme 47

Graph A. Diagnostic trouble code test active

Shows if the control module's diagnostic trouble code test is active or not. The blue surface indicates when the test is active. Not included as a status identifier.

Graph B. Malfunction active

Shows if the malfunction in the vehicle is active or not. The red surface indicates when the malfunction is present (active). Not included as a status identifier.

In the illustration, the control module has detected a malfunction in the second driving cycle, and this malfunction occurs a total of 4 times. Counters can be read out for every diagnostic trouble code in the control module which has this implemented. Driving cycles are indicated with vertical lines. A driving cycle often begins with ignition on and ends with ignition off.

Counter 1 (C#1). Counts number of driving cycles performed since the malfunction was confirmed last . As soon as a malfunction is detected and confirmed, the value is reset. When the malfunction is both detected and disappears in the second driving cycle (graph A), counter 1 will count up to 1 first in the following driving cycle (driving cycle 3), that is, a driving cycle has been run through since the last time the malfunction was confirmed.

In driving cycle 4, the counter is updated again, now to value 2. Just after that, the malfunction is detected (graph A), the malfunction is confirmed and the counter's value is reset. This sequence is repeated once again in driving cycle 5.

With other words, one can say that if the value is zero, the malfunction exists now or has existed earlier in the current driving cycle. If the vehicle is restarted (often requires ignition off and on again) in this position and the counter's value still is 0, then you probably have a permanent malfunction.

Values near zero indicate that the malfunction has been detected recently. It may also be that the malfunction exists but the diagnostic trouble code test has not started in these driving cycles, which means that the counter has not been reset. A high counter value indicates that the malfunction was last detected a number of driving cycles ago.

Counter 2 (C#2). Counts the number of driving cycles since the last confirmation of the malfunction and where the diagnostic trouble code was performed without detecting malfunction and confirmation of malfunction. Thus, when diagnostic trouble code is performed and no malfunction is detected, the counter will count up by 1 for every driving cycle. As soon as a malfunction is detected and confirmed, the value is reset.

When the malfunction is detected and disappears in the second driving cycle (graph A), counter 2 will count up to 1 first in the following driving cycle (run cycle 3). In driving cycle 4 the counter is updated again (diagnostic trouble code test has been run without detecting malfunction), now to value 2. Immediately after that the malfunction is detected (graph A), the malfunction is confirmed and the counter's value is reset. This sequence is repeated once again in driving cycle 5.

During driving cycle 6 and 7, the diagnostic trouble code test was run without detecting malfunction and the counter receives the value 2. In driving cycle 8, the diagnostic trouble code test is not run and thus the counter is not updated.

Counter 3 (C#3) . Counts the number of driving cycles performed since the malfunction was confirmed the first time. When a malfunction is confirmed the first time, the counter will count up by 1 for every subsequent driving cycle, regardless of if the malfunction is detected or not. Thus, the counter tracks the number of driving cycles since the malfunction was detected the first time. See graph where the counter increases by 1 for every subsequent driving cycle and the value of the counter is finally 6.

A low value indicates that the malfunction was detected for the first time relatively recently. However, a high value indicates that a first detection was performed some time ago.

Counter 4 (C#4). Counts the number of driving cycles in which the counter's value has been updated first when the malfunction was detected in the driving cycle. The counter has a final value of 3.

A certain indication of a malfunction's intensity can be obtained if you compare the value for counter 4 with counter 3. The closer the value for counter 4 the value is to the value of counter 3, the more frequent the malfunction.

Counter 5 warm-up (C#5). Counts the number of warm-up cycles that have been run since the malfunction light (MIL) has gone off. The counter is not shown in the illustration. Note! Only applies to emission-related systems.

Counter 6 malfunction detection (C#6). The counter counts the number of internal detections of the malfunction that have been run for the diagnostic trouble code. When this counter reaches value +127, the control modules decides that the malfunction is active right now.

When the counter is at value -128, the malfunction is not active. The value is reset for every new driving cycle.

If the value increases towards +127, the control module has detected a malfunction, and for every internal test the value is counted up. When the malfunction no longer exists, the control module counts down to minimum -128.

The value on the control module can only be changed when it has started the test for the diagnostic trouble code. How big each step is that the control module counts up or down the value by to reach the limits +127 or -128 may vary between control modules. Limits +127 and -128 are pre-defined limits in the control module.

In the graph, the counter first counts down to -128 when the diagnostic trouble code test starts. When a malfunction occurs (graph B) and the diagnostic trouble code test detects the malfunction, first the counter's value is reset to 0, then it scrolls up to +127. Only then the malfunction is considered to exist. If the malfunction disappears and the diagnostic trouble code test is active, the counter counts down to -128.

Counter 7 malfunction detection - max. current (C#7). Shows maximal value that counter 6 has in the present driving cycle.

The counter is not shown in the illustration.

Counter 8 malfunction detection - max. earlier (C#8). Shows maximal value that counter 6 has in the present and/or has had in earlier driving cycle.

The counter is not shown in the illustration.

Status Indicator

There are status indicator (status identifiers) that can be read out for every diagnostic trouble code. The control module tests every connection (signal) or function more or less periodically, depending on the self-diagnosis' conditions for start.

By reading out the diagnostic trouble code with associated status identifier, then you obtain status for the diagnostic trouble code test that detects the malfunction, as well as if the malfunction exists now or not.

Note. Status identifier, Counter and Frozen values are the most important factors to deciding the malfunction's nature, that is, to decide

1. when the malfunction was detected (frozen values, counters)
2. what the driving conditions were at the time (frozen values)
3. status for the test (self-diagnosis) (status identifier)
4. how frequent the malfunction is (counter).

All status identifiers (or malfunction detection counters) do not have to be introduced in one control module, this varies from system too system. All status identifiers restarts the count every time a new driving cycle/operation cycle starts or when erasing diagnostic trouble codes. Status identifiers should be read off continuously as the different identifiers can be updated later on.

The following describes possible status identifiers.

Note. Status identifiers for systems with diagnostics Volvo Diagnostic II is slightly different from status identifiers for diagnostic version Generic Global Diagnostics (GGD). See below.

When erasing diagnostic trouble codes, the diagnostic trouble code's status identifier is erased.

There are several ways to decide if the malfunction is active right now or not as well as when the malfunction occurred

1. Read off the diagnostic trouble code's counter, status identifier and frozen values. By interpreting these you can find out when the malfunction was stored, how often the malfunction has occurred (intermittence) and what the driving conditions were when the malfunction was stored.
2. Read off a parameter for component/system and decide if the value is correct or not. By, e. g., manually affecting the sensor or the switch, you can decide immediately if the parameter (signal) with its circuit is correct.
3. Trigger a component (activate) and decide if the component/function is affected or not. By triggering, e. g., the relay and listening for its clicking sound or the function which is to be affected, it is possible to decide immediately if the component is correct.
4. Decide if the vehicle shows any symptom (malfunction). If the vehicle no longer shows the symptom, one may suspect that the malfunction no longer is active.

The following accounts in detail for some of the above.

To decide the intensity of a malfunction

Note. Examples 1-5 (below) are based on counters for diagnostic concept Generic Global Diagnostic (GGD).

When a malfunction is intermittent or has unknown status, the diagnostic trouble code's counter is very useful to decide

1. How many driving cycles that have passed since the malfunction was detected the first time as well as since the malfunction was detected.
2. During how many driving cycles that the control module has detected the malfunction during a certain period, as well as how many driving cycles that the control module has not detected the malfunction. That the control module has not detected the malfunction may be due to the control module not having started the test for the malfunction, conditions to detect the malfunction are not fulfilled, or that the malfunction no longer exists.

The purpose of interpreting the counters is that it is possible to understand the malfunction's intensity, that is, show "how much" intermittent the malfunction is, as well as help in assessing if the chances to repeat the malfunction and customer symptom, and then succeed with troubleshooting.

If you read out the diagnostic trouble code information and it shows that the diagnostic trouble code test runs at least once every driving cycle (e. g., when driving), the counters' value may be very important when assessing the diagnostic trouble code's status and actions. However, if start of diagnostic trouble code test and its conditions are difficult to achieve, the counters' values should be considered to be of less importance.

Counters 1 and 3 show driving cycles. Counters 2 and 4 also show driving cycles, but then really a "share" of counters 1 and 3, respectively. In principle, counter 4 shows how many times that the customer should have detected symptoms.

Note. For systems with diagnostic concept Generic Global Diagnostics (GGD). If many diagnostic trouble codes are stored at the same time, then certain diagnostic trouble codes (the oldest) will have these frozen values/counters erased, this to save memory in the control module. These diagnostic trouble codes will then only have counter 2 left. Note also that counter 2 will also be erased when the memory is full, but often later than when other counters are erased.

Note. For system with diagnostic concept Volvo Diagnostics II. If many diagnostic trouble codes are stored at the same time, the control module keeps at least half of the oldest and half of the newest diagnostic trouble codes in the trouble code memory.

Note. For diagnostic trouble codes where the malfunction is not detected for many driving cycles and where the malfunction is detected again, then frozen values and counter values are written over with new values, that is, the diagnostic trouble code is considered "new".

Example 1, Intermittent malfunction

Scheme 48

1. Counter 1 = 5
2. Counter 2 = 2
3. Counter 3 = 25
4. Counter 4 = 10
5. Driving cycles

After the malfunction has been detected for the first time (driving cycle 0) the malfunction has been detected again in 9 of the first 20 driving cycles (counter 4 = 10). Using this, the conclusion can be drawn that in 11 driving cycles (20-9=11) the test has not been run or the malfunction has not been found, or a combination of these. After the last time that the malfunction was detected (in driving cycle 20), 5 driving cycles have passed (counter 1 = 5), where the test was run in 2 driving cycles without detecting a malfunction (counter 2 = 2).

Conclusion: Intermittent malfunction

Assessment: Good possibility to repeat the malfunction and customer symptom, and thus succeed with troubleshooting, as the malfunction has been found quite recently in several driving cycles.

Example 2, Permanent malfunction

Scheme 49

1. Counter 1 = 0
2. Counter 2 = 0
3. Counter 3 = 25
4. Counter 4 = 26
5. Driving cycles

After the malfunction has been detected for the first time (driving cycle 0) the malfunction has been detected again in all following driving cycles (counter 3 = 25, and counter 4=26).

Conclusion: Permanent malfunction

Assessment: Very good possibility to repeat the customer symptom and thus succeed with troubleshooting, as the malfunction has been found in every driving cycle. Since the malfunction has been detected during the present driving cycle (no. 26) it does not really matter for troubleshooting if the malfunction has been detected in all previous driving cycles or not.

The counter show more how "sure" the malfunction is as well as that it can confirm if the customer experienced the malfunction as the counter indicates.

Example 3, Intermittent malfunction

Scheme 50

1. Counter 1 = 122
2. Counter 2 = 122
3. Counter 3 = 125
4. Counter 4 = 4
5. Driving cycles

After the malfunction has been detected for the first time (driving cycle 0) the malfunction has been detected again in the 3 following driving cycles (counter 4 = 4). After the last time that the malfunction was detected (in driving cycle 3), 122 driving cycles have passed, where the test has been run in 122 driving cycles without detecting a malfunction.

Conclusion: Intermittent malfunction

Assessment: Not very good chance to repeat the malfunction and the customer symptom and thus succeed with troubleshooting, as the malfunction has only been detected in a few driving cycles a very long time ago.

The less driving cycles a malfunction has been detected in and the greater the number of driving cycles since the malfunction was detected the last time, the more difficult it is expected to be to repeat the malfunction and the customer symptom and thus succeed with troubleshooting.

This can be read off by the lower value is on counter 4 and the higher the value is on counter 1 and 2, as well as the lower the difference is between the value on counter 3 and counter 2, the more difficult it is expected to be to repeat the malfunction and the customer symptom and thus succeed with troubleshooting.

Example 4, Intermittent malfunction

Scheme 51

1. Counter 1 = 25
2. Counter 2 = 25
3. Counter 3 = 25
4. Counter 4 = 1
5. Driving cycles

After the malfunction has been detected for the first time (driving cycle 0) (counter 4=1), the malfunction has never been detected again. After the last time that the malfunction was detected, 25 driving cycles have passed, where the test has run in 25 driving cycles without detecting a malfunction.

Conclusion: Intermittent malfunction

Assessment: Not very good chance to repeat the malfunction and the customer symptom and thus succeed with troubleshooting, as the malfunction has only been detected in one driving cycle quite a long time ago.

Example 5 Unknown status

Scheme 52

1. Counter 1 = 25
2. Counter 2 = 0
3. Counter 3 = 25
4. Counter 4 = 1
5. Driving cycles

After the malfunction has been detected for the first time (driving cycle 0) (counter 4=1), the malfunction has never been tested and/or detected. After the last time that the malfunction was detected, 25 driving cycles have passed where the test has not been started. Since the diagnostic trouble code test has not started anymore, it cannot be decided if the malfunction exists or not.

Conclusion: Unknown status

Assessment: Read diagnostic trouble code information and try to achieve condition so that the diagnostic trouble code test is started and run, which makes it possible to detect the malfunction. If the malfunction is detected, chances are very good to repeat the customer symptom, and thus succeed with troubleshooting when the malfunction has been found in the current driving cycle.

If the malfunction was not detected even though conditions are fulfilled, then chances are less good to repeat the customer symptom, and thus succeed with troubleshooting as the malfunction has not been found in the current driving cycle.

Tools used for troubleshooting and diagnostics are divided into two different types, tools for Off Board Diagnostic (diagnostics outside the vehicle) or On Board Diagnostic (diagnostics system in the vehicle) where the control module's diagnosis is used.

There are several tools used for Off Board Diagnostics, a few intended for diagnosis of a control module and its systems are mentioned in this document.

Note. There are control modules with integrated diagnosis, where read-out of diagnosis only is possible with a built-in "tool". This applies to, e. g., climate control module MCC for model S70/V70/C70, where read-out takes place via light-emitting diode on the front of the panel. For, e. g., audio unit HU 1205 for model S40/V40, the audio unit is not connected to the diagnostics socket in the vehicle. All diagnostics as well as other settings are controlled directly by menus in the display.

Where do I find the information in VIDA

Information is found in VIDA.

Note. Information for older cars (model year -1998) is read out using Volvo System Tester, Diagnostic socket with light-emitting diode or Volvo Diagnostic Key.

Counter, status identifier and frozen values

Counter, status identifier and frozen values are always found in VIDA/DIAGNOSTICS/DIAGNOSTICTROUBLECODE. Can also be found in certain troubleshooting.

Parameters, dynamic are always found in VIDA/DIAGNOSTICS/CARCOMMUNICATION. Normally also found in troubleshooting.

Parameters, static are always found in VIDA/DIAGNOSTICS/DETAILS, VIDA/DIAGNOSTICS/NETWORK or VIDA/DIAGNOSTICS/CARCOMMUNICATION. Can also be found in troubleshooting.

Activations, Quick-tests

Activations and Quick-tests are found in VIDA/DIAGNOSTICS/CARCOMMUNICATION. Normally also found in troubleshooting.

Scheme 53

Function

Valve defective

If there should be a problem with a valve, the EVAP-valve opens to let in air to the engine through the canister.

Scheme 54

Control system for evaporation (EVAP)

A two-way valve (3.5 bar (50.8 psi) and the ORVR-valve in the hose to the canister are used to prevent overfilling of the tank, thus helping to prevent fuel from running into the canister.

The canister holds 2.08 liters (0.55 gallon).

Draining of the canister is controlled by the EVAP-valve, which is controlled by Engine control module (ECM).

When there is boost pressure the canister is ventilated to the turbo's inlet side. If there is no boost pressure, the canister is ventilated to the inlet manifold. This is controlled by the no-return valves.

Integrated recycling of fumes when refuelling (ORVR)

When refuelling, fuel fumes are collected in the EVAP-canister. The air that is let out flows through a small air filter (to prevent penetration of hydrocarbons) to the leak diagnostics pump. There it is released to the ambient air through another air filter.

The ORVR-valve closes when the tank is full. Some expansion capacity remains. The two-way valve, set to 3.5 bar (50.8 psi), is closed.

An extra hose that connects the tank sleeve and the tank's upper end prevents fuel from being pressed out when the fuel tank is pressurized.

Leakage diagnosis pump (LDP)

The pump is a spring and vacuum driven diaphragm pump. It is driven by a vacuum and is connected to the inlet manifold via a non-return valve.

The pump cycle is started by a short vacuum pulse that lifts the diaphragm and compresses the spring, which draws air into the space under the diaphragm through a non-return valve. At the same time, the canister's integrated breather valve closes. At the end of the pulse the vacuum is released by an electrically controlled valve and the spring force presses down the diaphragm, which pumps air into the tank-/EVAP-system through a second non-return valve. When the diaphragm is at the down stroke's end-position, the valve closes and the cycle starts again.

If there is no leak in the system, the pressure increases following a number of strokes and the system and pressure are equal. The pump stops working.

If there is a leak the "pulse interval" stabilizes at another level and Engine control module (ECM) will interpret this as a leak.

Scheme 55

Introduction

The fuel pump, fuel level sensor, and pressure regulator are installed in a single unit in the fuel tank. A spring is used to press down the unit against the tank's bottom, to absorb tolerances and changes in tank volume.

Quick-couplings are used in several places in the fuel system, e. g., by the pump unit, as well as pressure and return lines. No special tools are needed to open the couplings.

The fuel system can be drained in the same way as for S70/V70/C70, by using a special tool through the drain valves.

Function

The pump sucks in fuel mainly from the reservoir, pressurizes it, and leads it into the pressure line.

The return fuel is used to get fuel in to the reservoir. The return line ends in a restricted outlet, giving the fuel a high flow rate. This creates a low pressure in the reservoir's suction line, which means that fuel flows in to the reservoir from the fuel tank.

In reality, this arrangement means that pumping is done in two steps, first from the tank to the reservoir and then from the reservoir to the pressure line. Also, this minimizes the risk of air bubbles when cornering or when driving on steep grades with only a little fuel in the tank.

Scheme 56

S40/V40 uses a fuel system with return line, the purpose of which is to keep the fuel temperature below 50 °C (122 °F).

Two regulators are used to control pressure in the fuel rail

1. The return pressure regulator (5) is located beside the fuel tank. The fuel pressure at the outlet is kept at a value of 450 kPa (65.3 psi). The pressure regulator is of the spring type. The rest of the fuel is routed directly back to the fuel tank. To prevent fuel leaks (vapors) to the surroundings the valve is vented to the charcoal canister.
2. The pressure regulator on the fuel rail (6) keeps a constant pressure to the injectors of 410 kPa (59.5 psi).
3. This pressure regulator is dependent on the pressure in the inlet manifold.

Evaporative emission (EVAP) system

The hose between the canister and the fuel tank has a 1 mm (0.04 in) restriction, designed to prevent fuel in liquid form from reaching the canister when refuelling.

Draining of the canister is controlled by the EVAP-valve.

When there is boost pressure the canister is ventilated to the turbo's inlet side. If there is no boost pressure, the canister is ventilated to the inlet manifold.

The information in the document describes the engine management system EMS 2000 for turbo engines. It also applies to non-turbo engines although there may be differences in both design and function.

Scheme 57

Emergency mode (Limp-home)

Remarks

If signal is missing from the atmospheric pressure sensor, the value 90 kPa (130 psi) is used when calculating. This is comparable to an elevation of approx. 1000 meters (0.62 miles). This will lower the boost pressure slightly but will hardly be noticeable.

If a signal is missing from the mass airflow sensor (MAF), the air mass is calculated using the throttle's position and the RPM signal.

If signal is missing from the throttle position sensor (TPS), MAF will take over.

Scheme 58

Scheme 59

Fan control

The engine's cooling fan control (FC) has two speeds, both controlled by Engine control module (ECM). Cars with AC are also equipped with a condenser fan, also controlled by Engine control module (ECM).

Control is determined by the following input signals

1. engine's coolant temperature
2. car's speed
3. AC pressure
4. AC request from AC switch or automatic by ECC control module.

Condenser fan control

Control is determined by the following input signals

1. car's speed
2. AC pressure

AC compressor control

Control is determined by the following input signals

1. AC request from AC switch or automatic by ECC control module
2. engine's coolant temperature
3. AC pressure

The engine's load value is calculated using the mass air flow (MAF) sensor and RPM signal.

If the engine temperature sensor stops working, the condenser fan and cooling fan (FC) are run at speed 1. After start the engine's cooling fan (FC) will run for 2.5 min. with speed 1.

If the mass air flow (MAF) sensor stops working (no calculation of load), the cooling fan (FC) will run 10 min. after the ignition has been turned off.

The Limp-home value for a defective AC pressure sensor is 0 kPa. This means that the AC system will not operate.

After three full throttle signals (WOT) within 2 minutes, the AC remains engaged.

Fan and AC control

The engine's cooling fan will start with first speed under the following conditions

1. engine temperature increasing over 100 °C (212 °F) and car speed lower than 115 km/h (71,5 mph).
2. pressure in AC system increasing above 1600 kPa (218 psi) and car speed lower than 115 km/h (71.5 mph).
3. if engine temperature increases over 115 °C (239 °F) when the ignition has been turned off, the engagement time is 2.5 min.
4. if engine temperature increases over 105 °C (221 °F) when the ignition has been turned off and the engine's calculated load level is higher than the limit value, the engagement time is 10 min.

The fan will start with second speed under the following conditions

1. Engine temperature increasing over 115 °C (239 °F) and car speed higher than 115 km/h (71.5 mph) and fan has already been engaged for 5 seconds with speed 1.
2. Pressure in the AC system increasing over 2400 kPa (348 psi) and car speed is lower than 10 km/h and fan has already been engaged for 5 seconds with speed 1.

The condenser fan starts under the following conditions

1. If engine temperature increases over 110 °C (230 °F) and car speed is lower than 90 km/h (56 mph).
2. If pressure in AC system increases above 1000 kPa (145 psi) and car speed is lower than 90 km/h (56 mph).

The AC compressor will be turned off under the following conditions.

1. engine temperature increases over 125 °C (257 °F)
2. pressure in AC system drops below 200 kPa (29 psi) or increases above 3000 kPa (435 psi).
3. at full throttle (WOT) for 10 seconds.

Scheme 60

In principle, the turbo control is the same as the unit used on engine B5254T.

The wastegate valve, its pressure regulator being activated by the pressure at the turbo's outlet, controls the turbo's boost pressure. Even if the normal boost pressure is relatively low, the control module can increase the pressure above the basic setting by varying the control pressure via the turbo control valve (TCV). This means that the wastegate valve permits a higher boost pressure.

Normal boost pressure (approx. 130 kPa (18.9 psi) absolute pressure)

When the engine works with normal boost pressure, the wastegate's pressure regulator works with full outlet pressure from the turbo. When the boost pressure increases to max. permitted value, the wastegate's valve opens and part of the exhausts can be routed past the turbo to limit the boost pressure.

Modified boost pressure (max. 150 kPa (21.8 psi) absolute pressure)

When Engine control module (ECM) establishes that a higher boost pressure is needed (and is possible), the turbo control valve (TCV) opens and part of the pressure that acts on the wastegate's pressure regulator is routed to the turbo's inlet. The wastegate closes and the boost pressure increases. The connection cycle of the signal for the turbo control valve (TCV) is used to change permitted pressure level at the wastegate's valve.

Atmospheric pressure compensation

The atmospheric pressure sensor establishes at which elevation above sea level that the car is driven. To prevent the turbocharger from overspeeding in thin air the boost pressure is limited at elevations above 1000 m (0.62 mi). This is hardly noticeable.

When starting at high altitude the fuel mixture is reduced to compensate for the thinner air. The pressure sensor is used as an control of the turbo's boost pressure.

Emergency function (Limp-home)

To create possibilities in emergencies, the mass airflow sensor (MAF) can measure both air mass per hour and air mass per engine rev.

The boost pressure is not permitted to increase above the pressure's basic setting if

1. knocks occur. When knocking starts, ignition is delayed and fuel mixture is made richer. If this is not enough to eliminate knocking, the boost pressure is reduced.
2. engine temperature is too high (approx. 125 °C (257 °F), engine starts to knock. If this is confirmed, the turbo's boost pressure is reduced. (No direct detection of the engine's coolant temperature).
3. malfunction occurs on the turbo's control valve (TCV) or one of the hoses. This results in an emergency (limp-home) pressure of 30 kPa (4.4 psi).

Fuel injection is stopped if

1. boost pressure is too high, fuel shut-off is activated. This is calculated with a certain airflow measured by the mass airflow sensor.
2. turbo control valve (TCV) has jammed in open position.

Control of idle air

See Control of idle air

Detecting leakage and control of evaporation

See Detecting leakage and control of evaporation

Fuel pump

See Fuel pump

Fuel system

See Fuel system

See General

Input signals

See Input signals

Output signals

See Output signals

Turbo boost control

See Turbo boost control

See Control of idle air

See Detecting leakage and control of evaporation

See Fuel pump

See Fuel system

See General

See Input signals

See Output signals

See Turbo boost control