Tài liệu Toyota training course t852 engine control systems sec09

Technician Handbook 874 Engine Control Systems II Technical Training 169 Technician Handbook 874 Engine Control Systems II Thermostat Monitor The Thermostat Monitor measures the rate of coolant temperature rise. If the ECT sensor does not detect a predetermined temperature at the ECT sensor after a predetermined amount of time, the ECM will set one of several DTCs depending on the malfunction. The best source of this code-setting parameter information is the Repair Manual specific to the vehicle. Carefully study the information to determine what must occur before a DTC will be recorded and how to diagnose the issue. The DTC may be the result of an out-of-spec system monitor, not a component that has failed. P0116: Engine Coolant Temperature Circuit Range/Performance Problem P0125: Insufficient Coolant Temperature for Closed Loop Fuel Control NOTE Although the description in the Repair Manual for P0125 states “insufficient coolant temp for closed loop fuel control,” this can be one cause for no signal output from the O2 sensor. For most 2003 and earlier vehicles, the P0125 DTC is not a result of the thermostat monitor, and may correspond with O2 sensor heater malfunctions. For most 2004 and later vehicles, the P0125 DTC is a direct result of the thermostat monitor and corresponds with incorrect engine coolant temperature. P0128: Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature) Thermostat Monitor Diagnosis 170 When trying to determine the cause of a Thermostat Monitor issue, check the Freeze Frame data and duplicate the conditions. Use the Technical Information System (TIS) for Repair Manual (RM) and Electrical Wiring Diagram (EWD) information, and look for applicable Service Bulletins (SB). Technical Training Technician Handbook 874 Engine Control Systems II Exhaust Gas Recirculation (EGR) System Overview NOTE Exhaust Gas Recirculation (EGR) System Monitor The EGR system routes a small amount of exhaust gases back into the intake manifold, during certain engine operating conditions, to lower combustion chamber temperature and pressure. This helps control engine knock and reduces oxides of nitrogen emissions. Most vehicles equipped with VVT-i or Dual VVT-i systems will not utilize an EGR system. The EGR system is monitored because a system failure can affect emissions. The EGR valve position/temperature detection monitoring method is utilized to detect: •  Level of EGR flow (too much or too little) •  Component performance •  Sensor opens and shorts EGR DTCs (both 2-trip detection) are: •  P0401: Insufficient Flow ECM compares EGR temperature to IAT when EGR valve is open. Low EGR temperature is interpreted as a system fault. •  P0402: Excessive Flow ECM monitors EGR valve height position sensor. If EGR is off but sensor signals that valve is open, ECM assumes the valve did not close. Exhaust Gas Recirculation (EGR) System Diagnosis When trying to determine the cause of an EGR system issue, check the Freeze Frame data and duplicate the conditions. Use the Technical Information System (TIS) for Repair Manual (RM) and Electrical Wiring Diagram (EWD) information, and look for applicable Service Bulletins (SB). NOTE If the vehicle has been repaired in the past, verify that all EGR valve vacuum lines are routed correctly. Technical Training 171 Technician Handbook 874 Engine Control Systems II VVT-i Diagnosis The variable valve timing system is designed to control the intake and exhaust (on some systems) camshaft(s) to provide valve timing that is optimally suited to the engine conditions. This improves torque in all speed ranges, as well as increased fuel economy and reduced exhaust emissions. Camshaft timing is varied based on engine operating conditions such as intake air volume, throttle position, and engine coolant temperature. The ECM checks the actual valve timing based on input from the camshaft position sensor and the crankshaft position sensor. There are several types of variable valve timing systems in use on Toyota and Lexus vehicles, including VVT-i, Dual VVT-i, and VVT-iE. It is essential that the VVT system be correctly identified before beginning diagnosis. The best source for identifying the VVT system on a specific vehicle is the Repair Manual. VVT-i The VVT-i system phases only the intake camshaft and includes the ECM, the oil control valve (OCV), and the VVT controller (on the camshaft). The ECM controls the OCV duty-cycle, which in turn regulates the oil pressure supplied to the VVT controller. Because the VVT-i system relies on oil pressure to operate, valve timing will not be optimized when the engine is cold or at low engine speeds. Dual VVT-i VVT-iE 172 The Dual VVT-i system phases both the intake and exhaust camshafts and includes the same components as the VVT-i on all camshafts. The VVT-iE system uses electric motors to phase the intake camshafts. The exhaust camshaft is phased using the same components as the VVT-i system. Because the intake camshaft is phased by electric motors, it can optimize valve timing even when the engine oil pressure is low, such as when the engine oil temperature or the engine speed is low. Technical Training Technician Handbook 874 Engine Control Systems II VVT-i Monitors The VVT systems are monitored for many malfunctions. Always refer to the Repair Manual for specific system DTC and monitor information. The following is a summary of the Dual VVT-i system monitors: Camshaft Position Over-Advanced, OverRetarded, or System Performance The ECM sends a target duty-cycle control signal to the OCV. This control signal regulates the oil pressure supplied to the VVT controller. The VVT controller can advance or retard the intake camshaft. If the difference between the target and actual intake valve timing is large, and changes in the actual intake valve timing are small, the ECM interprets this as the VVT controller stuck malfunction and sets a DTC. See the Repair Manual for DTC information and monitor enabling conditions and details. Crankshaft Position – Camshaft Position Correlation To monitor the correlation of the intake camshaft position and crankshaft position, the ECM checks the VVT learning value while the engine is idling. The VVT learning value is calibrated based on the camshaft position and crankshaft position. The intake valve timing is set to the most retarded angle while the engine is idling. The exhaust valve timing is set to the most advanced angle while the engine is idling. If the VVT learning value is out of the specified range in consecutive driving cycles, the ECM illuminates the MIL and sets a DTC. See the Repair Manual for DTC information and monitor enabling conditions and details. Camshaft Position Sensor Circuit If no signal is transmitted by the VVT sensor despite the engine revolving, or the rotations of the camshaft and the crankshaft are not synchronized, the ECM interprets this as a malfunction of the sensor and sets a DTC. See the Repair Manual for DTC information and monitor enabling conditions and details. Camshaft Position Actuator Circuit After the ECM sends the “target” duty-cycle signal to the OCV, the ECM monitors the OCV current to establish an “actual” duty-cycle. The ECM detects a malfunction and sets a DTC when the actual duty-cycle ratio varies from the target duty-cycle ratio. See the Repair Manual for DTC information and monitor enabling conditions and details. Technical Training 173 Technician Handbook 874 Engine Control Systems II VVT Diagnosis When trying to determine the cause of a VVT system issue, check the Freeze Frame data and duplicate the conditions. Use the Technical Information System (TIS) for Repair Manual (RM) and Electrical Wiring Diagram (EWD) information, and look for applicable Service Bulletins (SB). Active Tests NOTE 174 Active tests can be performed to check the VVT system. Different active tests will be available depending on the VVT system. Typically, when the valve timing is changed at idle with an active test, the engine will run rough or may die. Refer to the Repair Manual for the proper VVT active test response and diagnostic procedure. Check the vehicle service history. If the vehicle has been repaired in the past, check for improperly installed timing belts, components, etc. Technical Training Technician Handbook 874 Engine Control Systems II ETCS-i Overview Instead of a conventional cable connecting the driver-operated throttle pedal to the engine throttle valve, the latest ETCS-i systems allow the ECM to adjust throttle angle in response to engine and vehicle conditions. The accelerator pedal position sensor detects accelerator pedal position (driver controlled) and signals the ECM. The ECM drives the throttle motor to change throttle valve position. The throttle position sensor detects throttle valve angle and confirms to the ECM that the desired throttle valve position is achieved. Both the accelerator pedal position sensor and the throttle position sensor have two sensing elements. ETCS-i Monitor ETCS-i Diagnosis The ECM uses two accelerator position sensors and two throttle position sensors to verify proper operation of the position sensors and to monitor the commanded versus actual throttle valve opening angle. When trying to determine the cause of an ETCS-i issue, check the Freeze Frame data and duplicate the conditions. Use the Technical Information System (TIS) for Repair Manual (RM) and Electrical Wiring Diagram (EWD) information, and look for applicable Service Bulletins (SB). The Techstream can display data readings from both sensing elements of the accelerator pedal position sensor and throttle position sensor. Compare actual sensor signals to specifications, with throttle pedal released and depressed. Normal signals indicate that sensors and all related circuits are operating correctly. Out-of-specification signals lead to wiring and component DVOM testing. Active tests can be performed to check the ETCS-i system. Refer to the Repair Manual for the proper ETCS-i Active Test response and diagnostic procedure. Technical Training 175 Technician Handbook 874 Engine Control Systems II PZEV Overview Early PZEV Vehicles NOTE Late PZEV Vehicles NOTE PZEV Diagnosis Under CARB PZEV requirements, the tailpipe emissions must meet the SULEV (Super Ultra-Low Emission Vehicle) regulations and the evaporative emissions must meet the PZEV (Partial Zero Emission Vehicle) regulations. Go to http://www.epa.gov/otaq/stds-ld.htm for more information on light-duty vehicle emissions regulations. The warranty for emissions components is increased to 150,000 miles (California). Some manuals may refer to the PZEV vehicle as having the “California Package.” While most PZEV vehicles will be sold and operated in California, they may show up in your shop. The differences between early model (2003–2006) PZEV and conventional vehicles are: an Intake Manifold Valve Assembly (IMVA), which is attached to a revised intake manifold, is incorporated; the front TWC is a close-coupled type (closer to exhaust ports for faster warm-up); the Toyota HCAC (Hydrocarbon Adsorptive Catalyst) is utilized as the rear TWC; two post-catalyst O2 sensors are used [one after the front TWC (S2 position) and one after the rear TWC (S3 position)]; and the EVAP system incorporates a larger canister and a new trap canister. Some early model PZEV vehicles may have two banks (B1 and B2) for a 4cylinder engine. The differences between later model (2006 and later) PZEV and conventional vehicles are: an Intake Manifold Valve Assembly (IMVA), which is attached to a revised intake manifold, is incorporated; and the front catalyst is a closecoupled type. Components for PZEV vehicles and conventional vehicles are not interchangeable. Verify correct part numbers, tag colors, electrical connector colors and shapes, etc. before installing new parts. When trying to determine the cause of a PZEV vehicle issue, check the Freeze Frame data and duplicate the conditions. Use the Technical Information System (TIS) for Repair Manual (RM) and Electrical Wiring Diagram (EWD) information, and look for applicable Service Bulletins (SB). Use the Repair Manual (RM) and New Car Features (NCF) manual to identify component locations and components that may be different than a conventional vehicle. 176 Technical Training Technician Handbook 874 Engine Control Systems II ECM Diagnosis Overview The ECM is rarely the cause of a problem. On rare occasions, you will find that the Malfunction Indicator Lamp or the Techstream fails to operate properly. Before connecting your Techstream it is important to confirm that the Malfunction Indicator Lamp (MIL) is functioning normally. A bulb check of the MIL is performed when the ignition is switched ON. If the MIL does not illuminate, it indicates that a problem exists in the MIL subsystem. This condition must be corrected before any further diagnostic work can be performed. See the diagnostic procedures for inoperative MIL in the Repair Manual. Once the engine is started, the MIL should turn OFF. If the MIL remains ON after the engine is running, the diagnostic system has detected a malfunction in the engine control system. Failure of Techstream to Establish Communications with ECM There are several possibilities when the Techstream fails to communicate with the vehicle. The problem could simply be the way you programmed the tester, or connecting to the wrong DLC. Once you have confirmed correct programming and proper lead connection, you will need to establish whether the problem is in the tester or the diagnostic circuit. To isolate a tester problem from a vehicle problem, simply try the tester on another vehicle. If the tester communicates normally with another vehicle, it is probably OK and the vehicle diagnostic system must be inspected. ECM Circuit Diagnosis If the MIL illuminates when the ignition is switched to the ON position, the Main Relay is functional and current is flowing to the ECM +B terminals. If the MIL does not illuminate, use a voltmeter to monitor the +B terminal of DLC1. If battery voltage is available at the DLC1 +B terminal, the Main Relay is functional. Further circuit troubleshooting will be required to determine if current is flowing to the ECM. Consult the Repair Manual. Refer to the appropriate Repair Manual circuit inspection charts and to the Engine Control System schematic in the EWD for troubleshooting details. Technical Training 177 Technician Handbook 874 Engine Control Systems II ECU Reprogramming Beginning with some 2001 model year vehicles, the ECM is capable of being reprogrammed. It is called ECU reprogramming because this procedure may be applicable for multiple processors. This procedure allows the ECM to be updated on an as-needed basis without replacement. If there is a calibration update available for a certain ECU on a vehicle, a linked “Yes” will be present in the Cal. Update? column of the particular ECU row within the Health Check Results screen (after a Health Check is performed). Clicking on the linked result will open TIS. The Service Bulletin (SB) related to the issue will be available and will provide the necessary reprogramming information and procedure. NOTE ECU Reprogramming Tips It is critically important that the TSB be followed exactly and in its entirety to avoid damage or creating other problems. •  If a Recalibration Label is present, the vehicle has already been recalibrated and no further action is required. •  The ECU calibration program is confirmed using the Techstream. •  Check battery voltage. To avoid battery fluctuations while reprogramming the Engine ECU, turn OFF all electrical accessories (i.e. radio, lights, interior fan). Confirm battery voltage is greater than 11.5V. Charge battery as necessary. NOTE 178 If battery voltage drops below 11.4V during ECU recalibration, damage to the Engine ECU will occur. Technical Training Technician Handbook 874 Engine Control Systems II NOTE The GR-8 battery charger includes a Power Supply mode designed to keep the battery at a constant 13.5 V and eliminate current spikes during ECU reprogramming. To enter this mode, turn the GR-8 ON  login  Main Menu  Power Supply. •  Ensure that all electrical systems are turned OFF and doors and trunk are closed. Once the recalibration process has started, do not operate the doors or accessories. •  Recalibration can take up to 45 minutes. The length of time to reprogram will vary, depending on the type of ECM and reprogram file. •  Do not move the Techstream or cable during recalibration to prevent recalibration failures. •  Confirm that the new recalibration has successfully installed. •  If applicable, attach a new Recalibration Label. Technical Training 179 Technician Handbook 874 Engine Control Systems II VC Circuit Diagnosis 180 The VC Circuit provides a constant 5V to many engine control sensors and components. If this circuit is shorted to ground, all sensors using this circuit for their 5V reference will show low readings (0V from signal wire) that do not change during any condition. Typically, the engine will not run with this condition or may run very rough or die often and the Techstream may not be able to communicate with the ECM. Sometimes, no DTCs will be present with this condition. This condition sometimes occurred on early model vehicles because the VC circuit was shorted to ground internally in the vapor pressure sensor. Simply unplugging the VPS returned all other sensors to normal operation and allowed the engine to run properly. If an engine is not running or is running very rough or dying and all sensors are showing shorted conditions (0V from signal wire), this may require diagnosis of the VC circuit. Technical Training Technician Handbook 874 Engine Control Systems II Immobiliser System Overview The immobiliser system is a theft deterrent system that determines whether to disable the SFI system based on a comparison of the key’s ID codes and the vehicle’s pre-registered code. If the ID codes do not match, the immobiliser system deactivates, and the SFI system and the engine cannot be started. There are many different immobiliser systems in use. When the Transponder Key ECU assembly detects that the key unlock warning switch is ON, the ECU provides current to the transponder key coil and produces a faint electric wave. A transponder chip in the key receives this wave, and in turn outputs a key ID code signal. The Transponder Key coil receives the signal, the transponder key amplifier amplifies the signal, and the signal is then transmitted to the ECU. The ECU matches the key’s ID codes with the vehicle’s ID code (previously registered in the ECU), and sends the results to the ECM. When the identification results show that the key’s ID code matches the vehicle’s ID code (and after the ECU has confirmed this match), the immobilizer system does not engage, allowing engine controls to function for fuel and spark control. The ECU also transmits a security signal that communicates “indicator OFF” to the Theft Warning ECU, and the security light turns OFF. Immobiliser System Diagnosis When trying to determine the cause of an immobiliser issue, use the Technical Information System (TIS) for Repair Manual (RM) and Electrical Wiring Diagram (EWD) information, and look for applicable Service Bulletins (SB). Immobiliser System Diagnosis Tips When starting the vehicle, make sure the key light (image in illustration) on the instrument cluster turns OFF. If the light does not turn OFF, this may indicate a problem with the immobiliser system. The ECM may set DTCs for immobiliser issues. Refer to the Repair Manual (RM) for the proper diagnostic procedure. Technical Training 181 Technician Handbook 874 Engine Control Systems II Hybrid Systems If an engine control issue is present on a hybrid vehicle, it may be necessary to place the vehicle into Inspection Mode. This will keep the engine running at all times so that diagnosis can be performed. Refer to the Repair Manual (RM) for the proper Inspection Mode procedure. The following is a general procedure to place hybrid vehicles into Inspection Mode: 1.  Turn the ignition switch ON. 2.  Fully depress the accelerator pedal twice with the transmission in the P position. 3.  Fully depress the accelerator pedal twice with the transmission in the N position. 4.  Fully depress the accelerator pedal twice with the transmission in the P position. 5.  Check that the “MAINTENANCE MODE” on the multi-information display and master warning light is illuminated in the combination meter. 6.  Put the vehicle in READY mode. NOTE To exit out of Inspection Mode, turn the ignition switch OFF. NOTE It is not recommended to drive the vehicle in Maintenance Mode as damage to hybrid components will occur. Hybrid System Diagnosis When trying to determine the cause of an engine control issue on a hybrid vehicle, check the Freeze Frame data and duplicate the conditions. Use the Technical Information System (TIS) for Repair Manual (RM) and Electrical Wiring Diagram (EWD) information, and look for applicable Service Bulletins (SB). 182 Technical Training Technician Handbook 874 Engine Control Systems II Technical Training 183