Contents: Description of the electronic engine… ↧ Description of the Throttle Actuator… ↧ Description of the camshaft position… ↧
Description of the electronic engine management system (ECM) controller
The ECM communicates with and monitors many other emission-related components and systems. OBD II diagnostics monitor the system's operation and sets a diagnostic trouble code (DTC) if it worsens.
Operation of the Malfunction Indicator Lamps and storage of DTCs depend on the type of DTC. Emissions-related DTCs are classified as Type A or Type B codes. Type C codes are not emissions-related.
The ECM is located in the engine compartment. The ECM is the control center of the engine management system. The ECM controls the following components:
- Fuel injection system
- Ignition system
- Emission control systems
- On-board diagnostic system
- Air conditioning and fans
- Throttle Actuator Control (TAC)
The ECM controller continuously monitors information from various sensors and other sources, as well as monitors systems that affect vehicle performance and harmful emissions. The ECM controller also performs diagnostic checks on various parts of the system. The ECM controller can detect performance problems and notify the driver using fault indicator lights. If the ECM controller detects a problem, it records a diagnostic fault code. The area to which the fault belongs can be determined by a specific DTC. This helps the technician when performing repairs.
Operation of the ECM controller
The ECM can supply 5V or 12V to various sensors and switches. This is done using resistors that pull the appropriate lines up to regulated power lines inside the ECM. In some cases, a regular serial voltmeter will not allow an accurate measurement due to the low internal resistance. Therefore, a digital multimeter with an input impedance of at least 10 megohms is required to accurately measure voltages.
The ECM controls the output circuits by supplying ground potential or supply voltage through the so-called output drivers.
EEPROM
Electrically Erasable Programmable Read-Only Memory (EEPROM) is a non-volatile memory device that is part of the ECM. The EEPROM stores programming and calibration information that the ECM needs to control the power circuits.
Reprogramming the ECM requires special equipment and appropriate software and calibration data.
Programming the anti-theft system frequency code
The vehicle is equipped with an anti-theft system that interacts with the ECM. If the ECM is replaced, the frequency code of the anti-theft module installed in the vehicle must be programmed into the new ECM. Without this procedure, the vehicle will not start.
Knock sensor module
The ECM controller constantly monitors the state of the detonation monitoring evaluation circuit using an integrated circuit. The Detonation Sensor module (KS) contains electronic circuits that allow the ECM controller to analyze the detonation sensor signals and diagnose the detonation sensors and their associated circuits. If the ECM controller detects that the knock sensor module does not read these signals, a diagnostic fault code is set.
Diagnostic connector
The Data Link Connector (DLC) is a 16-pin connector that allows a technician to read serial data links during diagnostics. By connecting a scan tool to this connector, a technician can monitor various serial data link parameters and display diagnostic trouble code information. The DLC is located in the driver's compartment, under the instrument panel.
Malfunction indicator lamp
The fault indicator light is located inside the instrument panel. The fault indicator light is controlled by the ECM controller and lights up when the ECM controller detects a condition that affects the vehicle's emission of harmful substances.
Precautions when servicing the ECM
The ECM is designed to handle the normal load currents encountered during vehicle operation. However, overloading of these circuits should be avoided. When checking for opens or shorts, do not ground or energize any ECM circuits unless instructed to do so. These circuits should only be tested with a digital multimeter.
After sales (additional) electrical and vacuum equipment.
Note: Do not connect additional vacuum-driven equipment to this vehicle. Installing additional vacuum-driven equipment may cause damage to vehicle components or systems.
Note: To avoid damage to the vehicle, additional electrical equipment must be connected to the vehicle's electrical system near the battery (both nutrition and weight).
After sales (additional) electrical and vacuum equipment is any equipment installed on a vehicle after it leaves the factory that connects to the vehicle's electrical or vacuum system. No provisions are made in the vehicle's design for installing such equipment.
Additional electrical equipment, even when installed in accordance with these strict requirements, may cause problems with the vehicle's electrical system. This may also include equipment not connected to the vehicle's electrical system, such as portable telephones and radios. Therefore, the first step in diagnosing any electrical system problems is to remove all aftermarket electrical equipment from the vehicle. If the problem persists, it is diagnosed in the usual manner.
Static electricity damage
Important: To prevent damage to the ECM from static electricity, DO NOT touch the ECM connector pins.
Electronic components used in control systems are often designed for very low voltages. Electronic components are easily damaged by electrostatic discharge. To damage some electronic components, an electrostatic voltage of less than 100 V is enough. For comparison, a voltage of 4000 V is needed for a person to even feel an electrostatic discharge.
A person can acquire an electrostatic charge in a number of ways. The most common are frictional electrification and electrostatic induction. For example, frictional electrification can occur when a person slides on a car seat.
Electrification by electrostatic induction occurs when a person wearing well-insulated shoes stands next to a highly charged object and briefly touches the ground. Like charges flow to the ground, leaving the person charged with a charge of the opposite polarity. Electrostatic charging can cause damage to electronic components, so it is important to exercise caution when handling and inspecting.
Inspection of devices under the hood
Important: This check is very important and must be carried out carefully and thoroughly.
Carefully inspect underhood devices when performing any diagnostic procedure or when diagnosing the cause of an emissions test failure. This can often resolve the problem without any additional action. When inspecting, follow these guidelines:
- Inspect the vacuum hoses - correct routing, pinches, cuts, disconnections.
- Inspect hard to reach hoses.
- Inspect the wires in the engine compartment for the following faults:
- Burnt or worn areas
- Pinched wires
- Touching sharp edges
- Touching hot exhaust pipes
Basic knowledge required
Note: Failure to understand the basic principles of this electrical system when performing diagnostic procedures may result in incorrect diagnosis or damage to electrical system components. Do not attempt to diagnose electrical system problems without this basic knowledge.
Basic hand tool skills are required to effectively use this section of the Service Manual.
To use this section of the service manual, you must have some basic knowledge of engine operation and electrical diagnostics.
- Basics of Electrical Circuits - You need to know the basics of electricity and understand voltage, current, and resistance. You need to understand what happens to an electrical circuit when it is open or shorted, and you need to be able to identify a shorted or open circuit with a digital multimeter. You need to be able to read and understand electrical diagrams.
- Using a digital multimeter - You need to be able to work with a digital multimeter - an extremely valuable device. You need to be able to measure voltage (V), resistance (Ohm), current (A), alternating signals with a multimeter (min/max.) and frequency (Hz).
- Use of Circuit Testers - Do not use a test light to test engine controls unless specifically instructed to do so. Be able to use component test jumpers and a digital multimeter without damaging the terminals. Be able to use the J 35616 connector test adapter kit and use the kit whenever diagnostic procedures instruct you to connect to the terminal side of the connector.
Description of the Throttle Actuator Control (TAC) System
The Throttle Control System (TAC) is used to improve emissions, fuel economy, and overall handling characteristics. The Throttle Control System (TAC) eliminates the mechanical coupling between the accelerator pedal and the throttle. The throttle Control System (TAC) eliminates the need for an automatic speed control system and an electric motor for controlling the idle air supply. The following is a list of components of the Throttle Control System (TAC):
- The accelerator pedal assembly includes the following components:
- Accelerator pedal.
- Accelerator Pedal Position (APP) Sensor 1.
- Sensor 2 APP.
- The throttle body assembly includes the following components:
- Throttle Position Sensor 1 (TP)
- Throttle Position Sensor (TP) 2
- Throttle actuator motor
- Throttle valve
- ECU controller
The ECM controller monitors the driver's acceleration requirement using 2 APP sensors. The voltage range of the sensor 1 APP is approximately 0.98... 4.16 volts, changing as the accelerator pedal moves from the initial position of the non-pressed pedal to the position of the pedal pressed to full speed. The range of the APP sensor 2 is in the range of approximately 0.49... 2.08 volts, changing as the accelerator pedal moves from the initial position of the non-pressed pedal to the position of the pedal pressed to full speed. The ECM controller processes this information along with other sensor inputs in order to send the throttle a command to take a certain position.
The throttle valve is controlled by a DC motor called the throttle actuator motor. The ECM can move this motor forward or in reverse by controlling battery voltage and/or ground to 2 onboard drivers. The throttle valve is held at its 7% home position by a constant force return spring. When no current is supplied to the throttle actuator motor, this spring holds the throttle valve in its home position.
The ECM monitors the throttle angle using 2 TP sensors. TP sensor 1 voltage changes from approximately 0.5 to 4.25 volts as the throttle valve moves from the 0 percent position to wide open throttle (WOT). TP sensor 2 voltage changes from approximately 4.45 to 0.7 volts as the throttle valve moves from the 0 percent position to wide open throttle (WOT).
The ECM runs a diagnostic that checks the voltage levels of both APP sensors, both TP sensors, and the throttle actuator motor circuit. It also monitors the return speed of both return springs, which are housed inside the throttle body assembly. These diagnostics run at different times depending on whether the engine is running or not and whether the ECM is in the process of learning throttle parameters.
Each time the ignition is turned on, the ECM performs a quick test of the throttle return spring to ensure that the throttle plate can return to the 7 percent home position from the 0 percent position. This is to ensure that the throttle plate can be returned to the home position in the event of a motor actuator circuit failure. Note that in cold temperatures, the ECM moves the throttle plate 7 percent with the ignition on and the engine off to remove any ice that may have formed on the throttle plate.
Throttle Position Re-Learning Procedure
The ECM stores a number of parameters, including the lowest throttle position (0%), the home position (7%), and the return speed of both springs. These values are only cleared or overwritten when the ECM is reprogrammed or when the throttle relearn procedure is performed. Note that if the battery is disconnected, the ECM will perform the throttle relearn procedure immediately after the ignition is turned on.
The throttle valve relearn procedure is performed each time the ignition is turned on if the engine has been off for more than 29 seconds and the following conditions are met:
- Engine speed is less than 40 rpm.
- The car's speed is 0 km/h (0 mph).
- Engine coolant temperature (ECT) is between 5-85°C (41-185°F).
- The intake air temperature is between 5-60°C (41-140°F).
- The accelerator pedal position sensor signal corresponds to an angle of less than 14.9%.
- Ignition voltage 1 is greater than 10 volts.
After 29 seconds, the ECM moves the throttle plate from the rest position to fully closed, then to approximately 10% open. This procedure takes approximately 6-8 seconds. If any malfunction occurs in the throttle control (TAC) mechanism, a diagnostic trouble code (DTC) is stored. At the beginning of the procedure, the TAC Learn Counter parameter on the scan tool should be 0 and should increase to 11 by the end of the procedure. If the counter does not start at 0 or end at 11, this indicates a malfunction; a DTC should be recorded.
TAC System Default Actions/Low Power Modes
The ECM controller has 2 low-power modes, which it can switch to if a malfunction is detected in the throttle position control system. If, at a certain position of the accelerator pedal, a malfunction is detected in the circuit of the accelerator pedal position sensor 1 or sensor 2, the throttle position sensor 2 or throttle position sensor 1, the ECM controller switches to one of two low-power modes. In this mode, the engine torque is limited, so that the vehicle cannot reach speeds above 100 km / h (60 mph). The ECM controller remains in this low-power mode for the entire ignition cycle, even if the fault is corrected.
If a malfunction is detected in the TP control circuits, a discrepancy between the commanded and actual TP, a return spring test failure, or a TP sensor 1 circuit malfunction, the ECM enters another reduced power mode. In this mode, the engine speed is limited to 2500 RPM and 3-6 randomly selected fuel injectors are turned off. The reduced power indicator is also commanded to turn on. The ECM remains in this reduced power mode for the entire ignition cycle, even if the malfunction is corrected. Note that if a TP sensor 1 or TP control circuit malfunction is detected with the engine idling, without the accelerator pedal depressed, the engine may stall.
Description of the camshaft position control system
The camshaft position control system allows the ECM to change the valve timing of all 4 camshafts while the engine is running. The camshaft position actuator unit (15) changes the camshaft position in response to changes in oil pressure. The camshaft position actuator solenoid valve changes the oil pressure, adjusting the advance or retardation of the camshaft. Changing the valve timing in response to changes in engine fuel consumption improves the following parameters:
- Engine output power
- Fuel consumption
- Reducing exhaust toxicity
The solenoid valve (7) of the camshaft position control system is controlled by the ECM. The change in the camshaft positions is controlled by the crankshaft position (CKP) sensor and the camshaft position (CMP) sensors. To calculate the desired camshaft positions, the ECM uses the following information:
- Engine Coolant Temperature (ECT) Sensor Signal
- Estimated Engine Oil Temperature (EOT)
- Mass Air Flow (MAF) Sensor Signal
- Throttle Position (TP) Sensor Signal
- Vehicle Speed Sensor (VSS) Signal
- Filling coefficient
Job
The camshaft position actuator unit is located in the outer casing and is driven by a timing chain. The unit has a rotor with fixed blades mounted on the camshaft. Oil pressure on the fixed blades causes the corresponding camshaft to rotate relative to the crankshaft. Moving the intake camshafts allows the intake valve advance to be set to 50 degrees of the crankshaft. Moving the exhaust camshafts allows the exhaust valve retardation to be set to 50 degrees of the crankshaft. When oil pressure is applied to the back of the blades, the camshafts return to 0 degrees of the crankshaft or to the top dead center (TDC). The ECM sends a command to the camshaft position control system solenoid to move the solenoid plunger and the spool valve so as to direct oil to the advance channel (11). Oil passing through the camshaft position control actuator from the advance passage of the solenoid creates pressure on the advance side of the camshaft position control actuator vanes. When the camshaft position is retarded, the camshaft position control solenoid valve directs oil to the camshaft position control actuator through the retard passage (3). The ECM can also command the camshaft position control actuator solenoid valve to stop supplying oil to both passages in order to fix the current camshaft position.
The ECM controls the camshaft position control solenoid valve by applying a pulse-width modulated control signal to the solenoid coil. The higher the duty cycle of the pulse-width signal, the greater the change in camshaft valve timing. The camshaft position control actuator also has a locking pin (14) that prevents the outer casing and the impeller assembly from moving relative to each other. Before the camshaft position actuator moves, the locking pin must be released by oil pressure. The ECM constantly compares the signals from the camshaft position sensors with the signal from the crankshaft position sensor, determining the positions of the camshafts and identifying malfunctions in the system. If there is a malfunction in the intake or exhaust camshaft position control actuator, the intake or exhaust camshaft position control actuator of the opposite bank of cylinders is set to the default position - 0 degrees crankshaft.
Operation of the camshaft position control system
| State of motion | Changing the position of the camshaft | Target | Result |
| Idling | No change | Minimizing valve overlap | Idle speed stabilization |
| Low engine load | Valve delay | Reduced valve overlap | Stabilization of engine output power |
| Average engine load | Valve advance | Increased valve overlap | Fuel economy and reduced exhaust emissions |
| Low to medium rpm under heavy load | Valve advance | Intake valve closing advance | Increased torque at low and medium speeds |
| High revs under heavy load | Valve delay | Intake valve closing delay | Increasing engine output power |