Toyota training course t852 engine control systems sec09

874 Engine Control Systems II Technician Handbook Thermostat Monitor The Thermostat Monitor measures the rate of coolant temperature rise.. P0116: Engine Coolant Temperature Circuit Ra

874 Engine Control Systems II

Technician Handbook

874 Engine Control Systems II

Technician Handbook

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 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)

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)

NOTE

Thermostat Monitor

Diagnosis

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Technician Handbook

Exhaust Gas

Recirculation (EGR)

System Overview

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

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)

If the vehicle has been repaired in the past, verify that all EGR valve vacuum lines are routed correctly

Exhaust Gas Recirculation

(EGR) System Monitor

NOTE

Exhaust Gas Recirculation

(EGR) System Diagnosis

NOTE

874 Engine Control Systems II

Technician Handbook

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

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

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

VVT-i Diagnosis

VVT-i

Dual VVT-i VVT-iE

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Technician Handbook

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:

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

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

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

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

VVT-i Monitors

Camshaft Position

Advanced,

Over-Retarded, or System

Performance

Crankshaft Position –

Camshaft Position

Correlation

Camshaft Position

Sensor Circuit

Camshaft Position

Actuator Circuit

874 Engine Control Systems II

Technician Handbook

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 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

Active Tests

NOTE

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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

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

ETCS-i Overview

ETCS-i Monitor

ETCS-i Diagnosis

874 Engine Control Systems II

Technician Handbook

PZEV Overview 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 4-cylinder 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 close-coupled 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

Early PZEV Vehicles

Late PZEV Vehicles

NOTE

NOTE

PZEV Diagnosis

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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

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

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

Failure of Techstream to

Establish Communications

with ECM

ECM Circuit Diagnosis

874 Engine Control Systems II

Technician Handbook

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

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

If battery voltage drops below 11.4V during ECU recalibration, damage to the Engine ECU will occur

ECU Reprogramming Tips

NOTE

NOTE

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