System overview ME 7.0

Transcription

1 "VCC EN " 1(21) System overview ME 7.0 The ME 7.0 (Motronic, Electronic 7.0) is a development of the Motronic 4.4 but also has strong similarities with the DENSO engine management system in terms of the components and their functions. The ME 7.0 is installed on all B52X4T engines from 1999 model year onwards. The largest new feature is the communication between the engine control module (ECM) and other modules via a network. There are also other new features in the system: Electronic throttle system which covers both the electronic throttle module and the accelerator pedal module Continuous Variable Valve Timing (CVVT) The following communicate with the engine control module (ECM) via the network: Transmission Control Module (TCM) Electronic Throttle Module (ETM) Antilock Braking System (ABS) Can and Driver information Module (CDM) Data Link Connector (DLC) ME 7.0 contains sensors which function according to known principles and send information by analog signals

2 "VCC EN " 2(21) Communication via network directly to the engine control module (ECM). As applies to controlled components these also function to known principles, with a few exceptions. These exceptions are covered on the following pages. CAN communication ECM (Engine Control Module) sends out and receives the following signals via the network: Can and Driver information Module (CDM) Is the "main computer" in the network and sends on required information to other modules. It also controls diagnostic communication by connecting the data link connector (DLC) to the network for programming/downloading and reading off diagnostic trouble codes (DTCs) and parameters. Transmission Control Module (TCM) The following signals are sent out on the network from the engine control module (ECM) and taken up by the TCM: Engine load Throttle opening Acknowledgement of torque limiting The following signals are sent out on the network from the Transmission Control Module (TCM) and taken up by

3 "VCC EN " 3(21) the ECM: Serial communication Input signals Torque limiting request stage I and II Request to operate the malfunction indicator lamp (MIL) Constant idle speed compensation (P/N position) signal Electronic Throttle Module (ETM) The following signals are sent out on the network from the electronic throttle module and taken up by the engine control module (ECM): Provides information about current throttle position Request via engine control module (ECM) to the CAN and Driver module to light the electronic throttle system lamp Faults discovered in the electronic throttle module are stored as diagnostic trouble codes (DTCs) in the Engine Control Module (ECM) Antilock Braking System (ABS) The following signals are sent out on the network from the ABS and taken up by the ECM: Vehicle speed signal, (goes via the CAN and diver module first) Data Link Connector (DLC) When reprogramming and downloading new software and faulttracing tracing with Volvo onboard diagnostic (OBD) system the initiation request is transferred from VIDA via data link connector (DLC) pin 7 also called Clink Communication link) to the Can and Driver information Module and closing two internal relays and opening communication with the network. ECM (Engine Control Module) communicates serially with the following: Immobilizer The request and exchange of information between the engine control module (ECM) and the Immobilizer. Data Link Connector (DLC) The serial communication via the data link connector (DLC) (pin 7, Cline) is only used by the authorities and certain other workshops in the USA/CDN for reading off OBD II codes using the Generic Scan Tool.

4 "VCC EN " 4(21) Number Component Information type/explanation Sensors and functions which are different to previous types are marked in bold text. 3/1 Ignition switch + 50 supply Provides early information to the Engine Control Module (ECM) to prepare for start. 3/4 Cruise control lever Gives information about selected speed to engine control module (ECM) via the electronic throttle module to control the throttle. The cruise control software in integrated into the engine control module (ECM). 3/9 Stop (brake) lamp switch Informs engine control module (ECM) that the car is braking. The signal is a safety feature in addition to the brake pedal sensor. The engine control module (ECM) carries out a range test between the signals from both sources. 4/30 4/6 ECC MCC 7/6 Oil pressure switch 7/8 air conditioning (A/C) pressure sensor (linear) Provides information if the air conditioning (A/C)is switched on or not. The engine control module (ECM) controls connection/disconnection of the compressor dependent on load, engine speed (RPM), engine coolant temperature, air conditioning (A/C) pressure. Provides information about engine oil pressure. The information is sent on to the Can and Driver information Module which lights the warning lamp. Provides information using a linear signal about any pressure changes on the highpressure side. Depending on the pressure the engine control module (ECM) can activate the engine cooling fan (FC) at high/low speed and shut off the air conditioning (A/C) compressor.the engine control module (ECM) can also provide information about low volume in the air conditioning (A/C) system. 7/15 Front heated oxygen sensor New signal characteristics.provides information about the oxygen level in (HO2S) (linear signal) the exhaust gases upstream of the catalytic converter.

5 "VCC EN " 5(21) 7/16 Engine coolant temperature sensor 7/17 Mass air flow (MAF) sensor (heated film principle) 7/21 Camshaft position (CMP) sensor 7/23 7/24 Knock sensor (KS) 1 Knock sensor (KS) 2 7/25 Engine speed (RPM)/position sensor 7/51 Accelerator pedal (AP) position sensor Provides information about engine coolant temperature (ECT). Located in the thermostat housing on the front edge of the engine. Provides information about the intake air mass. Has no resistor for the intake air temperature is complemented instead by a separate sensor 7/77 downstream of the charge air cooler (CAC). New signal characteristics.provides information about cylinder intake and compression phase. Gives shorter starting time, approximately 0.5 seconds. Provides information if the engine knocks.the engine control module (ECM) always knows each cylinders exact position from the new camshaft position (CMP) sensor. A turbocharged engine can be subjected to greater pressure variations in combustion chamber and must therefore have signals from 2 knock sensors (KS). Provides information about the crankshaft position and engine speed (RPM). Has flywheel adaptation for mechanical faults/damage. Like M 4.4 Provides information about current throttle opening.the signal is sent via two separate cables at the same time, one analog signal and one digital signal. 7/53 Low pressure sensor AC Provides information about pressure changes on the low pressure side. 7/73 Engine coolant level switch Provides information about engine coolant level. The information is sent further to the Can and Driver information Module which lights the low engine coolant level warning lamp. 7/77 Manifold absolute pressure (MAP) sensor 7/81 Manifold absolute pressure (MAP) sensor 7/82 Rear heated oxygen sensor (HO2S) Provides information about the intake air actual temperature after the charge air cooler (CAC). Used for boost pressure control. The sensor is used together with intake air pressure sensor 7/81. Provides information about the intake air actual pressure after charge air cooler (CAC). The most important sensor for boost pressure control. The sensor is used together with intake air temperature sensor 7/77. Provides information about the oxygen level downstream of the catalytic converter (TWC) front section.compared to previous versions it operates faster and can also affect the fuel/air mix to a greater extent. 7/84 Fuel tank pressure sensor Provides information about pressure changes in the fuel tank system. Used for leak diagnostic. 7/95 Ambient air pressure sensor (located in engine control module (ECM) 7/105 Ambient air temperature sensor Provides information about ambient air pressure. Affects injected fuel quantity at cold start at high altitude and leak diagnostic. Provides information about ambient air temperature. The signal is used to switch off the leak diagnostic in cold weather. 7/123 Clutch pedal position sensor Provides information that the clutch pedal is depressed and that the throttle should close. Used in certain markets to connect the so called Interlock function via VGLA which inhibits the starter motor. Also disconnects the cruise control. 7/124 Brake pedal sensor (located in the brake servo) CAN CAN communication Provides information that the brake pedal is depressed and that the throttle should be closed in case of serious faults in the Electronic throttle system in order to move to idling speed when the brake pedal is depressed. The signal is used to disconnect the cruise control. Exchange of information between the Engine Control Module (ECM) and the following units: ABS, TCM, CAN and driver module, electronic throttle module and DLC. Fuel trim

6 "VCC EN " 6(21) Control of the fuel/air mixture occurs using known principles. However the signal from the front probe is now of a linear character. This means that the engine control module (ECM) notices small changes throughout the voltage range and can control the fuel/air mixture much faster and more precisely than before. Both heated oxygen sensors (HO2S) contain as before a PTC resistor which is supplied with voltage from the engine control module (ECM) in order to reach operating temperature quickly. If the engine control module (ECM) determines that the ambient air is very cold and damp it may delay starting to heat up the heated oxygen sensors (HO2S) a few minutes. This is to prevent the heated oxygen sensor (HO2S) warm ceramic being touched by cold drops of water and then cracking. The oxygen sensitive ceramic which measures oxygen levels in the exhaust gases consists of Zirconium dioxide. Front heated oxygen sensor (HO2S) The output signal characteristic is between 0 4.7V. The shortterm fuel trim control lies between 0.75 and Signal characteristics: low voltage = rich mixture high voltage = lean mixture Rear heated oxygen sensor (HO2S) Camshaft Position (CMP) Sensor The rear heated oxygen sensor (HO2S) operates with the same signal characteristics as previously, but has gained more importance for controlling the fuel/air mixture. The rear heated oxygen sensor (HO2S) has been moved forward nearer to the front heated oxygen sensor (HO2S), just in front of the metal monolith in the catalytic converter. The camshaft position (CMP) sensor is a new version and operates using a different signal characteristic to previously. The sensor consists of an MRE (Magnetic Resistance Element). It is a permanent magnet with 2 special resistors which are connected in series with each other, where one end is voltage supplied and the other goes to ground. The output signal is an analog sine curve which passes through an analog/digital converter in the camshaft position (CMP) sensor before being sent on to the engine control module (ECM). When a tooth on the pulse wheel nears the sensor the

7 "VCC EN " 7(21) magnetic field is bent and affects the resistor located nearest to the ground, resistance affects the voltage and the output signal to the Engine Control Module (ECM) is low. When the same tooth continues past the sensor the magnetic field follows and so affects the other resistor which is located nearest to the voltage supply, this resistor affects the voltage so that the output signal to the Engine Control Module (ECM) is high. The magnetic field swings backwards and forwards between the teeth on the pulse wheel and the engine control module (ECM) senses the signals between the teeth, partly before and partly after the sensor. The pulse wheel has 4 teeth. The engine control module (ECM) calculates the time interval from one tooth to the next and can decide exactly which cylinder must be supplied with fuel and spark respectively. Functions/components controlled Number Component 2/11 Relay, engine cooling fan (FC) Signal type/function New sensors and functions which are different to previously known principles are marked with bold text. Engine cooling fan (FC) speed, high speed or low speed. 2/22 Air conditioning (A/C) Connecting and disconnecting air conditioning (A/C) compressor.

8 "VCC EN " 8(21) relay 2/23 Fuel pump relay Activation and deactivation of fuel pump. 2/32 System relay Controlled by the engine control module (ECM) provides engine sensors and functions with voltage supply. 4/30 4/6 ECC MCC 4/28 TCM Transmission Control Module Signals engine coolant temperature to climate control system which can then determine how the blower fan should be controlled after cold start. For signals transmitted between the engine control module (ECM) and the Transmission Control Module (TCM) refer to CAN communication. 4/50 ETM For signals transmitted between the engine control module (ECM) and the Electronic Throttle Module electronic throttle module refer to CAN communication. 5/1 CDM Can and Driver information Module 7/15 Front heated oxygen sensor (HO2S) 7/82 Rear heated oxygen sensor (HO2S) For signals transmitted between the engine control module (ECM) and the CAN and Driver information Module refer to CAN communication. Power supply for heating PTC element. Power supply for heating PTC element. 8/610 Injectors Controlled individually (sequentially). 8/18 Canister purge (CP) valve Continuously controlled, it controls the flow from EVAP canister to engine intake side. 8/19 Continuously Variable Valve Timing control valve (CVVT) 8/28 Turbocharger (TC) control valve 8/44 Fresh air valve, Canister purge (CP) 20/37 Ignition coil/power stage for cylinders 15 1 Malfunction indicator lamp (MIL) USA/CDN = Check Engine Other = engine symbol ETS warning lamp Cruise indicator lamp The Continuously Variable Valve Timing valve is continuously controlled by the engine control module (ECM) and controls the oil pressure to the variable camshaft on the exhaust side. Controls turbocharger (TC) boost pressure The valve is either off or on and opens or closes the canister fresh air intake during a leak diagnostic. Separate ignition coil with integrated power stages for each cylinder. Gives shorter charging interval and more power. The lamp lights up for faults affecting the emissions. The lamp flashes for misfires which cause risk of damage to the catalytic converter. Can also light up when requested by the Transmission Control Module (TCM) and the electronic throttle module. Can be activated by either the engine control module (ECM) or the electronic throttle module depending on where the fault was found in the system. Activated by the engine control module (ECM) and informs the driver that the cruise control is active. Continuous Variable Valve Timing (CVVT)

9 "VCC EN " 9(21) General The engine control module (ECM) continuously controls the Continuous Variable Valve Timing valve which in turn controls the CVVT unit with engine oil pressure. The Continuous Variable Valve Timing unit is mounted on the exhaust camshaft and is installed on all B52X4T engines. The control has 15 camshaft degrees (30 crankshaft degrees) between its outer positions. The variable camshaft is hydraulically controlled by the engine oil. The camshaft rotation takes place by the engine oil, using the Continuous Variable Valve Timing valve, transferring to either the Continuous Variable Valve Timing unit front (A) or rear (B) chambers. The chambers are divided by a piston which is fixed in the camshaft. When oil presses on the piston it results in a rotating motion in the piston because it installed in the Continuous Variable Valve Timing unit cover with splines. The pulse wheel for the timing belt is located on the Continuous Variable Valve Timing unit outer cover. The control is very fast and exact, it only takes approximately 500 ms to transfer between the outer positions. The Continuous Variable Valve Timing valve has very fine channels, for exact control and is therefore very sensitive to impurities. The variable camshaft main task is to minimize exhaust

10 "VCC EN " 10(21) emissions, mainly at cold start, but also gives an improved idling quality. Before the engine starts an internal check occurs as follows: When the when the ignition is switched on an electrical check is carried out on the signal cable, the power supply cable and the solenoid. The check is carried out for a shortcircuit to supply voltage/ground and opencircuit. The camshaft checks if it is in the correct position compared to the flywheel, when the camshaft is in its 0position (mechanical resting position). This can be done by comparing the signals from the camshaft position (CMP) sensor and the engine speed (RPM)/position sensor. If the deviations are too large between these the Continuous Variable Valve Timing valve does not activate and the diagnostic trouble code (DTC) is stored. In case of larger controlled deviations at the variable camshaft the time taken to regulate to the control value is measured. This time is used partially to determine how long it takes to alter the camshaft angle and partially to switch off the variable camshaft if the time exceeds a certain maximum time. The camshaft uses the engine oil and oil pressure to turn. The rotation time depends on engine speed (RPM), oil pressure, viscosity etc. which in turn depends on oil temperature and quality etc. To check that the camshaft position (CMP) sensor is correct it is compared to the signal from the engine speed (RPM)/position sensor when the engine turns. When the engine has started the check is interrupted. If the check gives faulty values a diagnostic trouble code (DTC) is stored and Continuous Variable Valve Timing control ceases. Continuous Variable Valve Timing (CVVT) valve

11 "VCC EN " 11(21) The Continuous Variable Valve Timing valve has three connecting channels and a return channel. Counted from the front of the valve these are: Return terminal Continuous Variable Valve Timing unit rear chamber terminal Engine lubricating system pressure terminal Continuous Variable Valve Timing unit front chamber terminal Continuous Variable Valve Timing (CVVT), function Inside the Continuous Variable Valve Timing valve there is a piston housing with a spring tensioned piston. The piston housing has three machined grooves with holes drilled into the piston housing center. The piston housing grooves are connected to the Continuous Variable Valve Timing valve three rear connections. The Continuous Variable Valve Timing valve piston has a channel connecting the pistons front and rear grooves in the center. The piston housing rear groove is connected to the valve return terminal. The front piston groove is wide enough that it can connect one of the piston housing outer groove with the center or stop in a center position where none of the outer grooves are connected.

12 "VCC EN " 12(21) In the unemployed position the Continuous Variable Valve Timing valve is in the rear most position (A) because of the valve spring. In this position the piston connects the piston housing center and rear grooves with each other. At the same time the piston has exposed the front piston housing groove so that it is connected to the valve return terminal. Then the oil pressure is guided from the Continuous Variable Valve Timing valve center terminal to the valves rear terminal. From there the pressure is led through the camshaft bearing into the camshaft rear oilway, via the camshaft center channel to the Continuous Variable Valve Timing unit hub. The hub is connected to the Continuous Variable Valve Timing unit front chamber. The pressure in the Continuous Variable Valve Timing unit hub thereby presses onto the Continuous Variable Valve Timing unit piston and presses it backwards. The piston is rotationally borne, via angle cut splines between the unit hub and cover. The camshaft toothed pulley wheel is installed on the cover and the camshaft is located in the hub. When the piston presses backwards the splines in the unit cover and hub rotate in relation to each other. The arrangement gives a gear ratio giving the piston the possibility of affecting the camshaft a lot with a small movement. The oil at the rear of the piston is pressed out through the outer hub channels into the camshaft and out through the camshaft upper front oilway The oil is led

13 "VCC EN " 13(21) further through the camshaft bearing, via the front Continuous Variable Valve Timing valve piston housing machining and back to the valve return terminal. When the Continuous Variable Valve Timing valve receives the signal to move to the other outer position (B) the pressure is led from the piston housing center terminal to the front terminal. The return oil is then sent through the rear piston housing machining to the center of the piston, via the piston rear machining and the piston center channel to the Continuous Variable Valve Timing valve return terminal. When the desired setting in the chamber is achieved the Continuous Variable Valve Timing valve moves to a central position where none of the terminals are connected with each other. When another camshaft setting in the required the Continuous Variable Valve Timing valve makes a short move in the necessary direction. In this way the Continuous Variable Valve Timing unit can continuously adjust the camshaft. Turbocharger (TC) control system B52X4T Turbocharger (TC) boost pressure is controlled by the boost pressure control (BPC) valve whose pressure regulator is affected by the pressure from the turbocharger (TC). The engine control module (ECM) determines current throttle angle and boost pressure to achieve the

14 "VCC EN " 14(21) calculated torque. The Engine Control Module (ECM) affects the controlling pressure using the turbocharger (TC) control valve. When the pressure increases the boost pressure control (BPC) valve pressure regulator is affected. When boost pressure has increased to the maximum permissible value the boost pressure control (BPC) valve opens and part of the exhaust gases bypass the turbocharger (TC) turbine which limits the boost pressure. Turbocharger (TC) control takes place constantly by measuring the current boost pressure and comparing it to the requested boost pressure. Controlling turbocharger (TC) boost pressure When the engine control module (ECM) determines that a higher boost pressure is permissible, the turbocharger (TC) control valve opens further and a proportion of the pressure acting on the boost pressure control (BPC) valve pressure servo is allowed through to the turbocharger (TC) inlet. In this way the control pressure is reduced, the boost pressure control (BPC) valve opens later and turbocharger (TC) pressure can increase. The engine control module (ECM) affects the turbocharger (TC) control valve by grounding one of the terminals with a fixed frequency where the signals duty cycle determines how much the valve should open and therefore how much the boost pressure can increase. Boost pressure reduction The charge pressure is reduced when driving in first gear and reverse with engine speed (RPM) below 3000 rpm to reduce the risk of wheel spin. If the engine has an automatic transmission the automatic transmission receives information from the TCM about when reduced charge pressure is required, for example when shifting. If the car has a manual transmission the Engine Control Module (ECM) determines which gear is selected based on the transmission and final drive gear ratios, engine speed (RPM) and vehicle speed. On cars with automatic transmission there is also boost pressure reduction in the winter mode. Boost pressure can also be reduced to protect the engine from damage. If the knock sensors (KS) detect that the engine is knocking above a given threshold value, and ignition has been retarded and the air/fuel mixture has been enriched, the Engine Control Module (ECM) will reduce the boost pressure until knock ceases. A reduction in boost pressure also takes place If There Is a risk of the engine overheating. If the Engine Coolant Temperature (ECT) sensor indicates that the temperature has exceeded 118 C, the Engine Control Module (ECM) lowers the boost pressure to reduce heat generation.

15 "VCC EN " 15(21) Automatic high altitude compensation Because the Engine Control Module (ECM) determines boost pressure using the signal from the intake air pressure sensor, there is automatic boost pressure control compensation when driving at altitude and in different temperatures. The engine power is not therefore noticeably affected by air density or temperature. When altitude exceed 2000 meter above sea level the engine control module (ECM) cannot compensate boost pressure any further because the air is too thin. Boost pressure monitoring The Engine Control Module (ECM) constantly monitors boost pressure using the mass air flow (MAF) sensor and the intake air pressure sensor. If boost pressure exceeds permitted levels the Engine Control Module (ECM) shuts the turbocharger (TC) control valve so that the engine torque can only be controlled through limiting the throttle opening. A diagnostic trouble code (DTC) is stored at the same time. If the calculations display too low boost pressure a diagnostic trouble code is stored. If a fault occurs in a component that affects boost pressure calculation, the Engine Control Module (ECM) will always limit throttle opening. If there is a fault in any of the sensors the boost pressure control goes over in an open loop. This means that it is controlled by fixed duty cycle which is a direct function of accelerator pedal (AP) position and engine speed (RPM). Return Fuel Lacking System (RFLS)

16 "VCC EN " 16(21) Return Fuel Lacking System The system has large similarities with the earlier version in the Motronic 4.4 and is market dependent. Some of the components have a new shape but function according to known principles. Leak diagnostic Vapor which evaporates from the fuel in the fuel tank is routed to and stored in the EVAP canister from where it is introduced into the combustion process via the canister purge (CP) valve and negative pressure in the intake manifold. A leak diagnostic has been introduced in certain markets to ensure that there are no leaks in the fuel tank system. The diagnostic is designed to detect leakage corresponding to a 1mm or larger hole. The fuel tank system consists of fuel tank, fuel filler pipe, EVAP canister, canister purge (CP) valve and all pipes between these components. To be able to diagnose the fuel tank system, it is also equipped with fuel tank pressure sensor and EVAP canister shutoff valve. Leak diagnostic different stages The diagnostic is divided into different phases in which the various components are tested. If a fault is detected in any of the phases the diagnostic is interrupted and the diagnostic trouble code (DTC) for the component

17 "VCC EN " 17(21) identified is stored. Diagnosis is carried out in the following stages: The fuel tank pressure sensor is checked for an unstable signal. Diagnostic trouble code (DTC) for a faulty fuel tank pressure sensor is stored if the signal deviates more than +/ 1 kpa more than 5 times in 5 seconds. The fuel tank pressure is checked so that it is stable and that the shortterm fuel trim is not too low. The EVAP canister shutoff valve closed and an evaporation check is carried out. By gauging how much fuel tank pressure increases value for how much fuel evaporates is provided, and this value is used later to calculate leakage flow. If fuel tank pressure sinks, this indicates that the canister purge (CP) valve is leaking and diagnostic trouble code (DTC) for an open canister purge (CP) valve is stored. The EVAP canister shutoff valve opens, the tank system is open. The canister purge (CP) valve is pulsed and because of the negative pressure in the intake manifold the engine starts to suck air through the EVAP canister. Because EVAP canister shutoff valve is open, the fuel tank pressure sinks slowly. If fuel tank pressure sinks rapidly this indicates that the EVAP canister shutoff valve is clogged and the diagnostic trouble code (DTC) for EVAP canister shutoff valve shut is stored. EVAP canister shutoff valve closes and the canister purge (CP) valve pulses with a duty cycle of approximately 17%. The pressure in the tank then falls to 1 kpa. If this pressure is not reached within 10 seconds it indicates a larger leak in the fuel tank. and the diagnostic trouble code (DTC) for a large leak is stored. If the fuel tank pressure does not change within 2 seconds it indicates a defective fuel tank pressure sensor or clogged piping.the diagnostic trouble code (DTC) for a large leak is stored. The canister purge (CP) valve is closed and the EVAP canister shutoff valve is still closed and there is negative pressure in the fuel tank. This negative pressure will decrease slowly. The decrease rate depends on fuel level, fuel evaporation and any leaks. Leakage flow is calculated by comparing pressure increase speed with the pressure decrease speed from stage 4 and by compensating for the evaporation measured in stage 2. If the calculated leakage flow exceeds a certain level this indicates a smaller leakage in the fuel tank system and diagnostic trouble code for small leak is stored. The EVAP canister shutoff valve opens, the EVAP function is enabled and the diagnostic test is finished. During the different phases when the system gauges whether the fuel tank system pressure acts normally or not, there are a number of circumstances which are

18 "VCC EN " 18(21) taken account of, for example: Diagnostics, faulttracing tracing the amount of fuel in the tank height above sea level fuel temperature and evaporation The system can calculate this information. Therefore it is not possible to describe how quickly or how much the pressure is permitted to increase or fall in the different phases. To carry out the diagnostic it is necessary that: there are no diagnostic trouble codes (DTCs) registered for: Vehicle speed signal, canister purge (CP) valve, EVAP canister shutoff valve and fuel tank pressure sensor fuel trim must be active engine idling Speed is 0 km/h the car is below 2500 meters above sea level outside temperature is above 8 C engine coolant temperature (ECT) must be above 8 C and below 120 C the pressure in the tank is above 1 kpa the concentration of fuel fumes in the EVAP canister must not be too high The diagnostic test starts at the earliest 17 minutes after the engine has started when all conditions have been fulfilled, and takes approximately 30 seconds. If the diagnostic is interrupted for any reason, the engine control module (ECM) will try to start again the next time all conditions are met. The engine control module (ECM) performs a maximum of 4 diagnostic attempts during an operating cycle. If no faults are detected the diagnostic is not active again until the engine is switched off and on again. If a fault is detected two further attempts are made to evaluate the fault.

19 "VCC EN " Diagnostics and fault tracing are carried out as before using VIDA. However from the 1999 model year onwards the Volvo Scan Tool (ST) (which could only communicate serially via the data link connector (DLC)) has been replaced by a new communication unit called the VCT 2000 (Volvo Communication Tool 2000) which can communicate with the modules via the network. Car communication Copyright 2004 Volvo Car Corporation. All rights reserved. The following can be read off during car communication. Read diagnostic trouble codes (DTCs) ME 7.0 engine management system contains approximately 135 diagnostic trouble codes (DTC). Each diagnostic trouble code (DTC) can give information on whether the fault depends on an opencircuit, shortcircuit to supply voltage or shortcircuit to ground. This gives a combined total of 405 different diagnostic trouble codes (DTCs). Activation The following output signals/components can be activated: Injectors (sequentially) Power stages/ignition coils (sequentially) air conditioning (A/C) relay (compressor clutch) Output signal engine coolant temperature sensor Indicator lamp CRUISE 19(21)

20 20(21) Misfire diagnostic Econometer signal to the Can and Driver information Module Engine cooling fan (FC) (High or low speed) Electronic Throttle System warning lamp EVAP canister shutoff valve Turbocharger (TC) control valve Canister purge (CP) valve Fuel pump (FP) relay Malfunction Indicator Lamp (MIL) Heating front heated oxygen sensor (HO2S) Heating rear heated oxygen sensor (HO2S) Continuous Variable Valve Timing (CVVT) camshaft control valve Interlock function (starter motor relay),usa/cdn only Reading off plotter Here curves and values for approximately 90 parameters can be read off. As before a maximum of 3 can be read at the same time. Activating diagnostic functions This is a new function for activating the different test phases in the following onboard diagnostic (OBD) systems: Return Fuel Lacking System (RFLS) If the fuel/air mixture does not ignite in the ignition stroke it can be said that the engine is misfiring. The flywheel is divided into 5 sectors where every sector corresponds to a special cylinder. The engine control module (ECM) detects misfires by registering the time between two sectors of the flywheel. The time between the two segments varies depending on: misfiring driveline oscillations normal variations caused by uneven combustion flywheel mechanical tolerances "VCC EN " The mechanical tolerances and drive line oscillations disrupt the signal and it is difficult to detect whether the engine is misfiring or not. To eliminate mechanical faults/damage to the flywheel the flywheel signal is adapted. Two crankshaft rotations are split into 5 intervals for 5 cylinder engines. The purpose of adaptation is to filter out the tolerances in the flywheel and resonance in the engine. By registering the time deviations between the sectors on the flywheel misfiring can be detected. In order for the engine control module (ECM) to be able to register misfires, the flywheel must be adapted. Misfire diagnostics are shut off until the flywheel is adapted for the first time. This adaptation value is saved and then used in subsequent operating cycles.

21 "VCC EN " 21(21) Adaptation of the flywheel is done when: engine speed is between 2300 rpm and 3000 rpm the load exceeds 40 % of relative load Flywheel adaptation takes approximately 60 seconds. Drive line oscillations, caused by uneven road surfaces for example, may lead to uneven engine operation (false misfiring). This is registered by the ABS module which sends this information to the engine control module (ECM) which uses this information in order to separate the oscillations from genuine misfiring. The misfire diagnostic is shut off when oscillations occur in the drive line caused by uneven road surfaces. Misfire diagnostics are also shut off when: leak diagnostic, when leak diagnostics are taking place diagnostic trouble codes (DTCs) in the engine speed (RPM)/position sensor, mass air flow (MAF) sensor, engine temperature sensor and the leak diagnostic and ABS. Misfiring lights the malfunction indicator lamp (MIL). In the event of misfiring, if there is risk of damage to the three way catalytic converter, the malfunction indicator lamp (MIL) will flash and then switch to a constant light. The engine control module (ECM) registers and stores which engine speeds and load ranges the misfiring occurred. Misfiring must occur within the same engine speed and load range again for a diagnostic trouble code (DTC) to be set. The malfunction indicator lamp (MIL) is lit if the diagnostic trouble code (DTC) for misfire is stored in the previous operating cycle and a new diagnostic trouble code (DTC) for misfire is received in the next operating cycle. If the misfire stops, the requirements for the rpm and load parameters must be met before the engine control module (ECM) will begin counting down to extinguish the warning lamp and erase stored diagnostic trouble codes (DTCs) for misfiring.