Engine Control System (Introduction): Overview Nissan Versa II

ENGINE CONTROL SYSTEM: Component Description

SYSTEM DESCRIPTION

The ECM performs ON/OFF duty control of the A/F sensor 1 heater corresponding to the engine operating condition to keep the temperature of A/F sensor 1 element within the specified range.

The ECM performs ON/OFF control of the heated oxygen sensor 2 heater corresponding to the engine speed, amount of intake air and engine coolant temperature.

OPERATION

ENGINE CONTROL SYSTEM: System Description

ECM performs various controls such as fuel injection control and ignition timing control.

Scheme 1

The amount of fuel injected from the fuel injector is determined by the ECM. The ECM controls the length of time the valve remains open (injection pulse duration). The amount of fuel injected is a program value in the ECM memory. The program value is preset by engine operating conditions. These conditions are determined by input signals (for engine speed and intake air) from the crankshaft position sensor, camshaft position sensor and the mass air flow sensor.

Firing order: 1 - 3 - 4 - 2

The ignition timing is controlled by the ECM to maintain the best air-fuel ratio for every running condition of the engine. The ignition timing data is stored in the ECM.

The ECM receives information such as the injection pulse width and camshaft position sensor signal. Computing this information, ignition signals are transmitted to the power transistor.

During the following conditions, the ignition timing is revised by the ECM according to the other data stored in the ECM.

1. At starting
2. During warm-up
3. At idle
4. At low battery voltage
5. During acceleration The knock sensor retard system is designed only for emergencies. The basic ignition timing is programmed within the anti-knocking zone, if recommended fuel is used under dry conditions. The retard system does not operate under normal driving conditions. If engine knocking occurs, the knock sensor monitors the condition. The signal is transmitted to the ECM. The ECM retards the ignition timing to eliminate the knocking condition.

Scheme 2

This system improves engine operation when the air conditioner is used.

Under the following conditions, the air conditioner is turned off.

1. When the accelerator pedal is fully depressed.
2. When cranking the engine.
3. At high engine speeds.
4. When the engine coolant temperature becomes excessively high.
5. When operating power steering during low engine speed or low vehicle speed.
6. When engine speed is excessively low.
7. When refrigerant pressure is excessively low or high.

CAN COMMUNICATION: System Description

CAN (Controller Area Network) is a serial communication line for real time application. It is an on-vehicle multiplex communication line with high data communication speed and excellent error detection ability. Many electronic control units are equipped onto a vehicle, and each control unit shares information and links with other control units during operation (not independent). In CAN communication, control units are connected with 2 communication lines (CAN H line, CAN L line) allowing a high rate of information transmission with less wiring. Each control unit transmits/receives data but selectively reads required data only.

Refer to " CAN COMMUNICATION SYSTEM: CAN COMMUNICATION SIGNAL CHART ", about CAN communication for detail.

Scheme 3

SYSTEM DESCRIPTION (EXCEPT FOR SINGLE CONNECTOR COOLING FAN WITHOUT A/C)

ECM controls cooling fan speed corresponding to vehicle speed, engine coolant temperature, refrigerant pressure, air conditioner ON signal. Then control system has 3-step control [HIGH/LOW/OFF].

Cooling Fan Operation

Scheme 4

Cooling Fan Relay Operation

The ECM controls cooling fan relays through CAN communication line.

SYSTEM DESCRIPTION (FOR SINGLE CONNECTOR COOLING FAN WITHOUT A/C)

ECM controls cooling fan speed corresponding to vehicle speed, engine coolant temperature, refrigerant pressure, air conditioner ON signal. Then control system has 2-step control [HIGH/OFF].

Cooling Fan Operation

Scheme 5

Cooling Fan Relay Operation

The ECM controls cooling fan relays through CAN communication line.

Scheme 6

1. The engine protection control at low engine oil pressure warns the driver of a decrease in engine oil pressure by the oil pressure warning lamp a before the engine becomes damaged.
2. When detecting a decrease in engine oil pressure at an engine speed less than 1, 000 RPM, ECM transmits an oil pressure warning lamp signal to the combination meter. The combination meter turns ON the oil pressure warning lamp, according to the signal.

Scheme 7

The fuel filler cap warning system alerts the driver to the prevention of the fuel filler being left uncapped and malfunction occurrences after refueling, by turning ON the fuel filler cap warning display on the combination meter.

ECM judges a refueled state, based on a fuel level signal transmitted from the combination meter.

When a very small leak is detected through the EVAP leak diagnosis performed after judging the refueled state, ECM transmits a fuel filler cap warning display signal (request for display ON) to the combination meter via CAN communication.

When receiving the signal, the combination meter turns ON the fuel filler cap warning display.

Reset Operation

The fuel filler cap warning lamp tunes OFF, according to any condition listed below

1. Reset operation is performed by operating the odo/trip meter switch (TYPE A) or [] switch (TYPE B) on the combination meter. Check the vehicle type to confirm the service information in Meter, Warning Lamp And Indicator article. Refer to " «INFORMATION»(ref-605949-S32272684842014032500000) ".
2. When the reset operation is performed, the combination meter transmits a fuel filler cap warning reset signal to ECM via CAN communication. ECM transmits a fuel filler cap warning display signal (request for display OFF) to the combination meter via CAN communication. When receiving the signal, the combination meter turns OFF the fuel filler cap warning display.
3. EVAP leak diagnosis result is normal.
4. Fuel refilled.
5. DTC erased by using CONSULT. NOTE: MIL turns ON if a malfunction is detected in leak diagnosis results again at the trip after the fuel filler cap warning display turns ON/OFF.

Scheme 8

SWITCH OPERATION

SET OPERATION

Press MAIN switch. (The CRUISE indicator in combination meter illuminates.) When vehicle speed reaches a desired speed between approximately 38 km/h (24 MPH) and 144 km/h (90 MPH), press COAST/SET switch.

ACCELERATE OPERATION

If the ACCEL/RES switch is pressed during the cruise control driving, increase the vehicle speed until the switch is released or vehicle speed reaches maximum speed controlled by the system.

And then ASCD will keep the new set speed.

CANCEL OPERATION

1. When any of following conditions exist, the cruise operation is canceled. CANCEL switch is pressed ASCD MAIN switch is pressed (Set speed is cleared) More than 2 switches at ASCD steering switch are pressed at the same time (Set speed is cleared) Brake pedal is depressed Selector lever is changed to N, P or R position Vehicle speed decreased to 13 km/h (8 MPH) lower than the set speed TCS system is operated
2. When the ECM detects any of the following conditions, the ECM cancels the cruise operation and informs the driver by blinking CRUISE indicator lamp. Engine coolant temperature is slightly higher than the normal operating temperature, CRUISE indicator lamp is blinked slowly. NOTE: Engine coolant temperature decreases to the normal operating temperature, CRUISE indicator lamp stop blinking and the cruise operation is able to work. Malfunction for some self-diagnoses regarding ASCD control: CRUISE indicator will blink quickly. When ASCD MAIN switch is turned to OFF during the cruise control driving, all of ASCD operations is canceled and vehicle speed memory is erased.

COAST OPERATION

When the COAST/SET switch is pressed during the cruise control driving, decrease vehicle set speed until the switch is released. And then ASCD will keep the new set speed.

RESUME OPERATION

1. When the ACCEL/RES switch is pressed after the cancel operation other than pressing ASCD MAIN switch is performed, vehicle speed is return to last set speed. To resume vehicle set speed, vehicle condition must meet following conditions. Brake pedal is released Selector lever is in other than P and N positions Vehicle speed is greater than 38 km/h (24 MPH) and less than 144 km/h (90 MPH)

Diagnosis Description

This system is an on board diagnostic system that records exhaust emission-related diagnostic information and detects a sensors/actuator-related malfunction. A malfunction is indicated by the malfunction indicator lamp (MIL) and stored in ECU memory as a DTC. The diagnostic information can be obtained with the diagnostic tool (GST: Generic Scan Tool).

DIAGNOSIS DESCRIPTION: 1st Trip Detection Logic and Two Trip Detection Logic

When a malfunction is detected for the first time, 1st trip DTC and 1st trip Freeze Frame data are stored in the ECM memory. The MIL will not illuminate at this stage. <1st trip>

If the same malfunction is detected again during the next drive, the DTC and Freeze Frame data are stored in the ECM memory, and the MIL illuminates. The MIL illuminates at the same time when the DTC is stored. <2nd trip> The "trip" in the "Two Trip Detection Logic" means a driving mode in which self-diagnosis is performed during vehicle operation. Specific on board diagnostic items will cause the ECM to illuminate or blink the MIL, and store DTC and Freeze Frame data, even in the 1st trip, as shown below.

DIAGNOSIS DESCRIPTION: Driving Pattern

DIAGNOSIS DESCRIPTION: System Readiness Test (SRT) Code

System Readiness Test (SRT) code is specified in Service $01 of SAE J1979/ISO 15031-5.

As part of an enhanced emissions test for Inspection & Maintenance (I/M), certain states require the status of SRT be used to indicate whether the ECM has completed self-diagnosis of major emission systems and components. Completion must be verified in order for the emissions inspection to proceed.

If a vehicle is rejected for a State emissions inspection due to one or more SRT items indicating "INCMP", use the information in this Service Information to set the SRT to "CMPLT".

In most cases the ECM will automatically complete its self-diagnosis cycle during normal usage, and the SRT status will indicate "CMPLT" for each application system. Once set as "CMPLT", the SRT status remains "CMPLT" until the self-diagnosis memory is erased.

Occasionally, certain portions of the self-diagnostic test may not be completed as a result of the customer's normal driving pattern; the SRT will indicate "INCMP" for these items.

Note. The SRT will also indicate "INCMP" if the self-diagnosis memory is erased for any reason or if the ECM memory power supply is interrupted for several hours.

If, during the state emissions inspection, the SRT indicates "CMPLT" for all test items, the inspector will continue with the emissions test. However, if the SRT indicates "INCMP" for one or more of the SRT items the vehicle is returned to the customer untested.

Note. If permanent DTC is stored or MIL illuminates during the state emissions inspection, the vehicle is also returned to the customer untested even though the SRT indicates "CMPLT" for all test items. Therefore, it is important to check SRT ("CMPLT"), DTC (No DTCs) and permanent DTC (No permanent DTC) before the inspection.

DIAGNOSIS DESCRIPTION: Permanent Diagnostic Trouble Code (Permanent DTC)

Permanent DTC is defined in SAE J1979/ISO 15031-5 Service $0A.

ECM stores a DTC issuing a command of turning on MIL as a permanent DTC and keeps storing the DTC as a permanent DTC until ECM judges that there is no presence of malfunction.

Permanent DTCs cannot be erased by using the Erase function of CONSULT or Generic Scan Tool (GST) and by disconnecting the battery to shut off power to ECM. This prevents a vehicle from passing the state emission inspection without repairing a malfunctioning part.

When not passing the state emission inspection due to more than one permanent DTC, permanent DTCs should be erased, referring to this information.

Note. The important items in state emission inspection are that MIL is not ON, SRT test items are set, and permanent DTCs are not included. Permanent DTCs do not apply for regions that permanent DTCs are not regulated by law.

DIAGNOSIS DESCRIPTION: Malfunction Indicator Lamp (MIL)

When emission-related ECU detects a malfunction in the emission control systems components and/or the powertrain control components (which affect vehicle emissions), it turns on/blinks MIL to inform the driver that a malfunction has been detected.

Scheme 9

1. The MIL illuminates when ignition switch is turned ON (engine is not running). NOTE: Check the MIL circuit if MIL does not illuminate. Refer to " «DIAGNOSIS PROCEDURE»(/nissan/versa/ii-2012-2014/remont/testing-diagnostics/#engine-control-system-diagnostic-codes-symptom-tests) ".
2. When the engine is started, the MIL should go off. NOTE: If MIL continues to illuminate/blink, perform self-diagnoses and inspect/repair accordingly because an emission-related ECU has detected a malfunction in the emission control systems components and/or the powertrain control components (which affect vehicle emissions).

DESCRIPTION

There are many operating conditions that lead to the malfunction of engine components. A good grasp of such conditions can make troubleshooting faster and more accurate.

In general, each customer feels differently about symptoms. It is important to fully understand the symptoms or conditions for a customer complaint.

Utilize a diagnostic worksheet like the WORKSHEET SAMPLE below in order to organize all the information for troubleshooting.

Some conditions may cause the MIL to illuminate or blink, and DTC to be detected. Examples

1. Vehicle ran out of fuel, which caused the engine to misfire.
2. Fuel filler cap was left off or incorrectly screwed on, allowing fuel to evaporate into the atmosphere.

Scheme 10

Scheme 11

When replacing ECM, this procedure must be performed.

Accelerator Pedal Released Position Learning is a function of ECM to learn the fully released position of the accelerator pedal by monitoring the accelerator pedal position sensor output signal. It must be performed each time harness connector of accelerator pedal position sensor or ECM is disconnected.

Throttle Valve Closed Position Learning is a function of ECM to learn the fully closed position of the throttle valve by monitoring the throttle position sensor output signal. It must be performed each time harness connector of electric throttle control actuator or ECM is disconnected or electric throttle control actuator inside is cleaned.

Idle Air Volume Learning is a function of ECM to learn the idle air volume that keeps each engine idle speed within the specific range. It must be performed under any of the following conditions

1. Each time electric throttle control actuator or ECM is replaced.
2. Idle speed or ignition timing is out of specification.

Scheme 12

1. PRECONDITIONING Make sure that all of the following conditions are satisfied. Learning will be cancelled if any of the following conditions are missed for even a moment. Battery voltage: More than 12.9 V (At idle) Engine coolant temperature: 70 - 100°C (158 - 212°F) Selector lever: P or N (CVT), Neutral (M/T) Electric load switch: OFF (Air conditioner, headlamp, rear window defogger) For vehicles equipped with daytime light systems, perform one of the following procedures before starting engine not to illuminate headlamps. Apply parking brake Set lighting switch to the 1st position Steering wheel: Neutral (Straight-ahead position) position Vehicle speed: Stopped Transmission: Warmed-up CVT models With CONSULT: Drive vehicle until "FLUID TEMP SE" in "DATA MONITOR" mode of "TRANSMISSION" system indicates less than 0.9 V. Without CONSULT: Drive vehicle for 10 minutes. M/T models Drive vehicle for 10 minutes. Do you have CONSULT? YES: GO TO 2. NO: GO TO 3 .
2. IDLE AIR VOLUME LEARNING With CONSULT Perform ACCELERATOR PEDAL RELEASED POSITION LEARNING. Refer to " «WORK PROCEDURE»(ref-605934-S21245521882014032500000) ". Perform THROTTLE VALVE CLOSED POSITION LEARNING. Refer to " «WORK PROCEDURE»(ref-605934-S19939682792014032500000) ". Start engine and warm it up to normal operating temperature. Select "IDLE AIR VOL LEARN" in "WORK SUPPORT" mode with CONSULT. Touch "START" and wait 20 seconds. Is "CMPLT" displayed on CONSULT screen? YES: GO TO 4. NO: GO TO 5.
3. IDLE AIR VOLUME LEARNING Without CONSULT NOTE: It is better to count the time accurately with a clock. It is impossible to switch the diagnostic mode when an accelerator pedal position sensor circuit has a malfunction. Perform ACCELERATOR PEDAL RELEASED POSITION LEARNING. Refer to " «WORK PROCEDURE»(ref-605934-S21245521882014032500000) ". Perform THROTTLE VALVE CLOSED POSITION LEARNING. Refer to " «WORK PROCEDURE»(ref-605934-S19939682792014032500000) ". Start engine and warm it up to normal operating temperature. Turn ignition switch OFF and wait at least 10 seconds. Confirm that accelerator pedal is fully released, turn ignition switch ON and wait 3 seconds. Repeat the following procedure quickly five times within 5 seconds. Fully depress the accelerator pedal. Fully release the accelerator pedal. Wait 7 seconds, fully depress the accelerator pedal and keep it for approx. 20 seconds until the MI stops blinking and turned ON. Fully release the accelerator pedal within 3 seconds after the MI turned ON. Start engine and let it idle. Wait 20 seconds.: GO TO 4.
4. CHECK IDLE SPEED AND IGNITION TIMING Rev up the engine two or three times and make sure that idle speed and ignition timing are within the specifications. For specification, refer to " «IDLE SPEED»(/nissan/versa/ii-2012-2014/remont/testing-diagnostics/#engine-control-system-diagnostic-codes-symptom-tests) " and " «IGNITION TIMING»(/nissan/versa/ii-2012-2014/remont/testing-diagnostics/#engine-control-system-diagnostic-codes-symptom-tests) ". Is the inspection result normal? YES: INSPECTION END NO: GO TO 5.
5. DETECT MALFUNCTIONING PART Check the following Check that throttle valve is fully closed. Check PCV valve operation. Check that downstream of throttle valve is free from air leakage. Is the inspection result normal? YES: GO TO 6. NO: Repair or replace malfunctioning part.
6. DETECT MALFUNCTIONING PART Engine component parts and their installation condition are questionable. Check and eliminate the cause of the incident. It is useful to perform "TROUBLE DIAGNOSIS - SPECIFICATION VALUE". Refer to " «DESCRIPTION»(/nissan/versa/ii-2012-2014/remont/testing-diagnostics/#engine-control-system-diagnostic-codes-symptom-tests) ". If any of the following conditions occur after the engine has started, eliminate the cause of the incident and perform Idle Air Volume Learning all over again: Engine stalls. Erroneous idle. : INSPECTION END

This describes how to erase the mixture ratio self-learning value. For the actual procedure, follow the instructions in "Diagnosis Procedure".

See also:
• DIAGNOSIS PROCEDURE