DESCRIPTION
The Electronic Concentrated Engine Control System (ECCS) is a computerized emission, ignition, and fuel control system. A single electronic control unit (ECU) monitors a variety of sensors, including the following
- Mass Airflow Meter
- Crankshaft Angle Sensor
- Temperature Sensor
- Detonation Sensor (Turbo Models)
- Exhaust Gas Oxygen Sensor
- Park/Neutral Switch
- Throttle Valve Switch
- Vehicle Speed Sensor
- Air Temperature Sensor
- Fuel Temperature Sensor
- Vacuum Control Sensor
- Power Steering Oil Pressure Switch
The computer processes information from these sensors and controls the following engine functions
- Air Injection
- Air Regulator Control
- EGR Operation
- Engine Idle Speed
- Fuel Injectors
- Fuel Pump Operation
- Ignition Timing
- Mixture Ratio
- Denotation
- Fuel Pressure
- Auxiliary Air Control
- Airflow Meter Self-Cleaning
- Spark Plug Switching
- Mixture Heating
- Canister Purge
- Self-Diagnosis (Fail-Safe Operation)
ELECTRONIC CONTROL UNIT (ECU) OPERATION
The ECU consists of a microcomputer, inspection lights, a diagnostic mode selector (or on/off switch), connectors and wiring or signal input, signal output and power supply. (Scheme 36) The unit is not serviceable and should not be opened. Monitor lights are provided on side of unit so system operation can be checked. The control unit contains memory and logic circuits that enable it to interpret sensor inputs and control various engine systems. On Maxima, Pulsar, Sentra, Stanza and Van models, ECU is located under the passenger seat. On Stanza Wagon models, the ECU is located under the drivers seat. On 200SX models, the ECU is located behind the left kick panel. On 300ZX models, ECU is located behind the right kick panel.
COMPONENT LOCATION
Note. Vehicles may not contain all ENGINE SENSORS that are listed, nor may they control all ENGINE CONTROLS that are listed. To determine which components are involved in each vehicle's control system, refer to the applicable system components illustration and/or applicable wiring diagram for the vehicle your working on. (Scheme 26)- (Scheme 35).
Maxima ECCS Component Locations. Scheme 26
Pulsar NX ECCS Component Locations. Scheme 27
Pulsar NX SE ECCS Component Locations. Scheme 28
Sentra ECCS Component Locations. Scheme 29
Stanza ECCS Component Locations. Scheme 30
Stanza Wagon ECCS Component Locations. Scheme 31
Van ECCS Component Locations. Scheme 32
200SX SE ECCS Component Locations. Scheme 33
200SX XE ECCS Component Locations. Scheme 34
300ZX ECCS Component Locations. Scheme 35
AIRFLOW METER
Nissan uses two types of airflow meters. The first type uses a swinging door that measures all air flow through it. The amount of door movement is detected by a potentiometer. The second type measures airflow by detecting the electrical current relationship to the amount of heat that is dissipated from a hot wire (located in path of incoming air). The more incoming air entering through the airflow meter, the more heat removed from the hot wire. The more heat removed from hot wire the less the resistance of the hot wire. The ECU evaluates the air flow rate through this change in resistance of the hot wire.
CRANKSHAFT ANGLE SENSOR
The crankshaft angle sensor monitors engine speed and piston position. The crankshaft angle sensor, which is built into the distributor, has a rotor plate and a wave-forming circuit. The rotor plate has 360 small slits, each determines crankshaft angle (one slit for each degree of rotation) and 4 or 6 large slits at 90 or 60 degrees each, to determine engine speed (4 slits at 90 degrees on 4 cyl., 6 slits at 60 degrees on 6 cyl.).
When the signal rotor plate passes the space between the Light Emitting Diode (LED) and photo diode, the slit in the signal rotor plate alternately cuts the light which is sent to the photo diode from the LED. This causes a pulsating voltage, which is converted into an on-off pulse by the wave-forming circuit and sent to the control unit.
CYLINDER HEAD TEMPERATURE SENSOR
A cylinder head temperature sensor is built into the cylinder head near the thermostat housing. The sensor monitors changes in temperature through resistance readings of a thermistor. The thermistor, which is incorporated in the sensor, provides a varying resistance measurement as engine temperature changes.
AIR TEMPERATURE SENSOR
Air temperature sensors are installed in the air cleaner housing and sense the temperature of incoming air. A thermistor, which is sensitive to changes in temperature of incoming air, is used to increase or decrease its resistance in response to temperature rise or fall. The ECU interprets these signals and adjusts its output control signals accordingly.
DETONATION (KNOCK) SENSOR
The detonation sensor is located on the engine cylinder block. It sends a signal to the ECU when "knocking" occurs. The control unit modifies ignition timing to reduce detonation.
VEHICLE SPEED SENSOR (VSS)
The vehicle speed sensor provides a vehicle speed signal to the ECU. The speed sensor consists of a reed switch, which is installed in the speedometer unit and transforms vehicle speed into a pulse signal. On digital type speedometer models, the sensor consists of an LED, photo diode, shutter and wave forming circuit. Its principle is the same as that of the crank angle sensor.
EXHAUST GAS OXYGEN SENSOR (O2 SENSOR)
This component measures the amount of unburned oxygen in the exhaust gas. It provides a voltage signal which is used to adjust fuel mixture (amount of injection time), so that proper combustion occurs.
FUEL TEMPERATURE SENSOR
The fuel temperature sensor is built into the pressure regulator and senses fuel temperature. When the fuel temperature is higher than the specified level, the ECU enriches the fuel being injected.
THROTTLE VALVE SWITCH (TVS)
The throttle valve switch is attached to the throttle chamber and actuates in response to the accelerator pedal movement. This sensor is a kind of potentiometer, which transforms the throttle valve position into output voltage and inputs this voltage signal to the ECU. It contains idle contacts and full-throttle contacts. The idle contacts are used for engine control. When throttle is at idle, idle contacts are closed. At any other throttle position a varying voltage signal is sent to the ECU in accordance with throttle valve opening and closing position.
VACUUM CONTROL VALVE
The vacuum control valve is provided to reduce engine lubricating oil consumption when intake manifold vacuum increases due to very high level deceleration. The vacuum control valve senses manifold vacuum, as vacuum increases beyond a predetermined point, the valve opens allowing air to be pulled directly into the intake manifold.
POWER STEERING OIL PRESSURE SWITCH
This switch is attached to the power steering high pressure tube and detects the power steering load, sending a load signal to the ECU. When oil pressure gets to a predetermined point, the ECU will send a signal to idle speed control valve to increase idle speed to assist with the power steering load.
FUEL INJECTION CONTROL
The ECU calculates base injection pulse width by processing signals from the crank angle sensor and airflow meter. After receiving signals from each sensor that detects various engine conditions, the ECU adds enrichments, which are preprogrammed into the control unit, to the base injection width. This makes the optimum mixture available throughout a wide variety of conditions. Fuel enrichment is always available under the following conditions: during warm-up, starting, after idle, under heavy load and when cylinder head temperature is high.
This fuel injection system incorporates mixture ratio feedback. It is designed to maintain the mixture ratio a precise point. Through the use of an exhaust gas sensor located in the exhaust manifold, the ECU can determine whether to richen or lean out the air/fuel ratio to precisely control exhaust emissions. This takes place during closed loop operation and continuously monitors itself to stay within an acceptable emissions output range. However, this system is overridden and will operate under open loop when one or more of the following conditions exist: starting, engine and exhaust sensor are cold, driving at high speeds or under heavy load, at idle, exhaust gas sensor monitors a too lean condition for over 10 seconds, fuel shut-off in operation, exhaust gas sensor is malfunctioning or pressure regulator control system is in operation.
Two methods of fuel injection are used. They are simultaneous and group injection. In simultaneous injection, fuel is injected into all 6 cylinders at the same time. In group injection, the 6 injectors are divided into 2 groups and fuel is injected into each group of injectors separately. When any of the following conditions are met, fuel injection shifts from group to simultaneous: engine speed more than 300 RPM, cylinder head temperature is below 140°F (60°C) and during starting.
IGNITION TIMING CONTROL
Ignition timing is controlled by the ECU depending upon engine operating conditions. Optimum ignition timing for each driving condition has been pre-programmed into the ECU. The ECU receives electrical signals from its operating sensors which are processed within the logic circuit. After determining present driving condition and optimum timing signal for that condition, the ECU outputs a signal to the power transistor, which in turn controls timing advance or retard.
DETONATION FEEDBACK OPERATION
The retard system, controlled by denotation sensor, is designed exclusively for turbocharged engines. The retard system does not work under normal operating conditions. However, if engine knock occurs, the detonation sensor monitors the knocking condition and sends a signal to the ECU. After receiving the signal, the ECU retards the ignition timing to eliminate the knocking condition.
IDLE SPEED CONTROL (ISC)
Engine idle speed is controlled by the ECU depending upon engine operating conditions. The ECU senses engine operating conditions and determines the best idle speed. Under any (depending upon system) of the following conditions the ECU will send an on signal to compensate idle speed: starting to 20 seconds after start, low battery voltage, headlights on, heater switch on, rear defogger on, power steering oil pressure switch on, radiator fan switch on, during deceleration and vehicle moving at idle. The ECU then sends an electronic signal to either the idle-up solenoid or the Auxiliary Air Control (AAC) valve (depending upon system) to either reduce or increase idle speed.
EXHAUST GAS RECIRCULATION (EGR) CONTROL
To lower exhaust gas nitrogen oxide emissions, an exhaust gas recirculation system is incorporated within the ECCS. This is accomplished by returning some exhaust gas from the exhaust manifold to intake manifold and then the combustion chamber to be reburned. This is controlled through the EGR valve and EGR control solenoid.
Under some or all of the following conditions the EGR system does not operate: engine starting, throttle valve switch on, under heavy load, low engine temperature, high engine temperature and high engine speeds. Except under the previously named conditions, when the ECU signals the EGR control solenoid, it energizes the coil within the solenoid which pulls the plunger downward and shuts off the vacuum signal to the EGR valve.
FUEL PUMP CONTROL
Fuel pump on and off and voltage variation control is accomplished through the ECU. Depending upon the system in use, control is accomplished by either varying voltage to the fuel pump or by turning fuel pump relay on or off. Some systems incorporate air regulator and fuel pump on and off controls simultaneously.
Fuel pump on and off control takes place as follows: ignition switch in "ON" position (operates for 5 seconds), engine running and/or cranking and engine stopped (stops in one second). Fuel pump voltage is approximately 9.4-13.4 volts except under the following conditions. Under these conditions, fuel pump voltage is approximately 13.4 volts: 5 seconds after ignition switch is turned off, during engine cranking, 30 seconds after engine starts, high engine temperature with idle switch off and low engine temperature.
AIR INJECTION VALVE (AIV) CONTROL
The air injection system is designed to send secondary air to exhaust manifold to reduce exhaust emissions (HC and CO). The system consists of an air injection valve, AIV control valve and AIV solenoid valve. The air injection valve is designed for one-way use and consists of a one-way reed valve.
When the ECU senses a vacuum signal created by excessive exhaust pressure pulsations from the exhaust manifold, it sends a signal to the AIV solenoid valve to activate the AIV control valve. The control valve opens up and allows air to enter the exhaust system upstream of the 3-way catalytic converter. This system also operates during deceleration for the purpose of blowing water off around the air injection valve.
FUEL PRESSURE REGULATOR CONTROL
This system is designed to improve hot engine startability by cutting off intake manifold vacuum and increasing fuel pressure. When coolant temperature is above a preset limit and engine speed is lower than 2500 RPM or with a light load, the ECU sends a signal to pressure regulator control solenoid valve. The electronic signal from the ECU energizes the coil inside of the pressure regulator control valve and pulls the plunger downward. This cuts off intake manifold vacuum and the positive pressure produced by pump is sent to the pressure regulator, therefore increasing fuel pressure. On some models, the fuel line is supplied with high pressure which is stored in a surge tank.
AIR REGULATOR CONTROL
The air regulator provides an air by-pass when engine is cold for purposes of fast idle during warm-up. A bi-metallic heater and rotary shutter valve control the rate of by-passing air. When the bi-metallic heater and shutter are cold, air by-pass port is open. As engine starts and an electrical current is permitted to flow through the bi-metallic heater, it warms up and closes the air by-pass port.
Some systems incorporate air regulator and fuel pump on and off controls simultaneously. Fuel pump and air regulator on and off control takes place as follows: ignition switch in "ON" position operates for 5 seconds), engine running and/or cranking and engine stopped (stops in one second).
AUXILIARY AIR CONTROL VALVE (AAC)
The ECU processes signals from monitoring sensors to determine the optimum idle speed under varying engine conditions. The ECU senses engine condition and determines the best idle speed from each cylinder head temperature sensor and the transaxle gear position. It then sends an electrical on-off signal that corresponds to the difference between actual idle speed and optimum idle speed. The AAC valve then regulates the amount of by-passing air by monitoring the length of time that the electrical on signal is presented.
AIRFLOW METER SELF-CLEANING CONTROL
This system is designed to heat the "hot wire" of the airflow meter after ignition switch is turned to the "OFF" position. This is to clean any foreign matter that may have adhered to it during operation. After the engine has stopped, the ECU sends a signal to heat the "hot wire" to 1832°F (1000°C) to burn off any foreign material under the following conditions: if engine reached a certain predetermined RPM, vehicle speed reached a minimum MPH, coolant temperature was between two preset standards and only when engine is stopped by ignition key (not stalled).
SPARK PLUG SWITCHING CONTROL
The spark plug switching system is designed to change ignition system firing from 2 spark plugs to one spark plug. This takes place during heavy load driving conditions to reduce engine noise. When coolant temperature is greater than a predetermined amount and engine is cranking or under a light load, a 2 spark plug ignition system is in effect. If coolant temperature is greater than a predetermined amount and the engine is operating under a heavy load, the ignition system is switched to a one spark plug type ignition system. When coolant temperature is less than a certain preset temperature, no matter what engine operating conditions take place, a 2 spark plug system is in effect.
MIXTURE HEATER CONTROL
The mixture heater is located between the throttle valve and the intake manifold. It is designed to atomize fuel during cold engine starts. The ECU controls the on and off cycles of the mixture heater. When the coolant temperature is less than a preset minimum and the engine is running the ECU will send an on signal to the mixture heater. The mixture heater will remain on several minutes after coolant temperature has reached the minimum temperature preset requirement.
If airflow meter output voltage is less than or greater than the preprogrammed valve, the ECU senses an airflow meter malfunction. The ECU then temporarily takes its driving conditions information from the throttle sensor. During this period of time, the ECU limits the RPM of the vehicle to a predetermined amount. This serves to alert the vehicles driver that the vehicle is driving under fail-safe conditions and needs attention.
If the cylinder head temperature sensor circuit is open, the ECU will hold the injector pulse width to a preset amount. This preset amount is equivalent to when the cylinder head temperature is between 68°F (20°C) and 176°F (80°C), therefore allowing the vehicle to reach its destination.
FUEL PUMP
If the ECU senses that the fuel pump circuit is malfunctioning, it will energize the fuel pump relay until the engine is stopped. Permitting the vehicle to reach its destination before repairing the problem.
INJECTOR MALFUNCTIONING
When the ECU senses that engine speed is less than a predetermined amount in the alternating injection mode (except during acceleration) and that injection pulse angle (crank angle) is less than a preset amount and at least one injector does not inject fuel 4 times in a row due to electrical problems, it determines there is an injector failure. If only one injector fails, the ECU will permit the vehicle to start and drive, but only to a predetermined maximum RPM. When the engine reaches this maximum RPM it will not go faster, indicating the fail-safe system is in effect and telling the driver mechanical attention is needed.
The self-diagnosis system is used in diagnosing problems and/or malfunctions of major sensors and actuators of the Electronic Concentrated Engine Control System (ECCS). There are 5 modes of diagnosis within the system. Before selecting any mode of self-diagnosis, always perform the PRELIMINARY CHECKS first or diagnosis may be incorrect.
MODE 1: MIXTURE RATIO FEEDBACK CONTROL MONITOR "A"
During closed loop operation, Green inspection light turns on when a lean condition is detected. Green light goes off when a rich condition is detected. During open loop operation, Green inspection light stays off. See MODES 1 & 2 MIXTURE RATIO MONITORS A & B CHART.
MODE 2: MIXTURE RATIO FEEDBACK CONTROL MONITOR "B"
The Green inspection light functions the same as in Mode 1. During closed loop operation, Red inspection light turns on and off simultaneously with Green inspection light when mixture ratio is being controlled within the specified range. During open loop, Red inspection light stays off. See MODES 1 & 2 MIXTURE RATIO MONITORS A B CHART.
MODE 3: SELF-DIAGNOSIS
- The ECU constantly monitors the operation of sensors and actuators, regardless of ignition key position. When a malfunction is suspected, the information can be retrieved from system memory by turning the diagnostic mode selector (or on/off on Van models to "ON" position) on the side of ECU. (Scheme 36)
- When properly activated, the Red and Green LED lights will flash appropriately to signal the number of the malfunctioning part(s). First the Red light will flash and then the Green light will follow. Red light flashes refer to number of tens in the code number. Green light flashes refer to number of ones in the code number.
- All codes are classified in 2 digit code numbers. For example, if Red light flashes once and Green light flashes twice, code 12 is detected. If diagnostic code(s) have been obtained, refer to the SYSTEM INSPECTION TABLE that applies to the model vehicle your working on and perform the test that it refers you to.
- If no diagnostic codes are obtained, define the driveability symptom and refer to the DRIVEABILITY INSPECTION TABLE that applies to that vehicle (perform Mode 4 first). There you will find a list of common driveability symptoms, find the symptom that your vehicle is exhibiting and check all the components in that column as well as any tests listed.
- If engine cranks, but fails to start, crank engine more than 2 seconds prior to starting self-diagnosis. Do not erase stored memory codes prior to self-diagnosis or intermittent malfunctions will be lost. Stored memory is lost if battery is disconnected or if Mode 4 is selected after Mode 3.
Electronic Control Units. Scheme 36
MODE 4: SWITCHES ON-OFF DIAGNOSIS
During this mode the inspection lights monitor certain switch on-off conditions and store this information in ECU memory. The switches being monitored are the throttle switch, starter switch and the vehicle speed sensor. To test operation of the throttle switch and/or starter switch while in mode 4 of self-diagnosis, observe the Red LED light on the ECU. Each time ignition switch is turned from "ON" to "OFF" position or "OFF" to "ON" position, Red LED light should blink on or off each time switching is detected. To test the vehicle speed sensor while in mode 4 of self-diagnosis, observe Green LED light of ECU. When vehicle speed is less than 12 MPH, the Green light should be off. When vehicle speed exceeds 12 MPH, Green light on ECU should illuminate.
MODE 5: REAL TIME DIAGNOSIS
This mode is used to detect problems within the active system. The moment a malfunction is detected the display lights will present malfunctioning code immediately. Making this mode of inspection advantageous because the condition can be found by observing the inspection lights during the actual driving conditions under which the malfunction takes place.
TEST PRELIMINARY CHECKS
Note. Prior to performing any self-diagnostics or engine related testing, perform all preliminary tests first. Set all adjustments to specifications listed on vehicle emissions decal.
- Check idle speed with automatic transmissions in "DRIVE" position. Set idle speed at middle engine speed (approximately 2000 rpm) on all models. On Maxima, 200SX, and 300ZX models, Green inspection light should flash 5 or more times during 10 seconds.
- On Pulsar models, while in Mode 2 of self-diagnostics, look for simultaneous flashes from Red and Green inspection lights.
- On Pathfinder and Pickup (VG30i), while in Mode 2 of self-diagnostics, Red and Green inspection lights should flash simultaneously 5 or more times during 10 seconds.
- On Pathfinder, Pickup (Z24i) and Van models, Red and Green inspection lights should flash simultaneously 7 or more times in 10 seconds. On Stanza and Stanza Wagon models, Red and Green inspection lights should flash simultaneously 9 or more times in 10 seconds.
- Perform idle speed switch test. Idle speed should increase to the amount specified in the IDLE SWITCH SPEED INCREASES chart when idle speed switch is turned from "OFF" to "ON" position. If idle is not as specified, adjust accordingly. IDLE SWITCH SPEED INCREASES Model Automatic "N" Position Manual RPM + or - Maxima 250 250 150 Pulsar (1) (1) (1) Stanza 250 250 150 Stanza Wagon 250 250 150 200SX 250 250 150 300ZX 250 250 150 (1) "ON" position at Idle and "OFF" position when accelerator pedal is depressed.
- On all models, perform a test drive to evaluate the effectiveness of any adjustments that may have been made. On Pulsar, Maxima, 200SX and 300ZX models, perform a MODE 5 REAL TIME DIAGNOSIS during the test drive to determine if any additional problems exist. Write down any diagnostic codes which appear.
- On all models, perform a MODE 3 SELF-DIAGNOSIS test. Write down any diagnostic codes which appear during the mode 3 test. If the results of the test drive, MODE 5 REAL TIME DIAGNOSIS test and/or MODE 3 SELF-DIAGNOSIS test are unsatisfactory (codes are presented), refer to diagnostic reference charts. For distinct component problems (diagnostic codes), see applicable SYSTEM INSPECTION CHART. For driveability problems, see applicable DRIVEABILITY INSPECTION CHART.
- After all replacements and/or repairs are completed, test drive the vehicle. This will give you a chance to evaluate the vehicles performance after the diagnosis and repair procedure is completed.
STARTING & CHANGING MODES OF SELF-DIAGNOSIS
On all models except Pathfinder and Van, turn ignition switch to "ON" position. Turn diagnostic mode selector of ECU fully clockwise and wait for inspection lights to begin flashing. (Scheme 36) On Pathfinder, Pickup and Van models, turn ignition switch to the "ON" position. Turn diagnostic mode selector to the "ON" position and wait for inspection lights to begin flashing. (Scheme 36)
On all models, count the number of flashes. Right after the number of flashes which correspond to the diagnosis mode you wish to enter appears, immediately turn the mode selector (mode on-off switch to "OFF" position for Pathfinder, Pickup and Van models) fully counterclockwise.
MEMORY ERASE
| CAUTION | Be sure all needed diagnostic codes are extracted from the ECU memory before disconnecting battery or switching from mode 3 into mode 4. |
Note. If ignition switch is turned to "OFF" position in any mode of diagnosis, then turned to "ON" position after ECU has completely lost power, the diagnosis mode will automatically return to mode 1, but memory will not be erased.
Stored memory will be erased if battery is disconnected or mode 4 is selected after mode 3. Only if mode select switch is turned counterclockwise (mode on-off switch to "OFF" position for Pathfinder, Pickup and Van models) after mode 3 and then after mode 4 is selected, will stored memory be erased. However, if mode selector switch is turned fully clockwise (on-off switch turned to "ON" position for Pathfinder, Pickup and Van models), diagnosis modes will continue to change in order until a certain mode is selected, this does not erase the stored memory.
TESTING CAUTIONS
Before connecting or disconnecting ECU harness connector to or from the ECU, be sure that ignition switch is in the "OFF" position and negative battery cable is disconnected or damage to the ECU may result. This is important because battery voltage is applied to the ECU even when the ignition switch is in the "OFF" position.
When performing an ECU input/output signal inspection, remove pin terminal retainer from connectors. This will make probing of the connector pins much easier and safer.
When connecting or disconnecting pin connectors from the ECU, take care not to bend or break any pin terminals.
Before replacing ECU, perform the ECU input/output signal inspection to be sure ECU is malfunctioning.
Modes 1 & 2 Mixture Feedback Control Monitors A & B Chart. Scheme 37
Key to Symbols. Scheme 38
| Codes | Models | Component |
|---|---|---|
| 11 | All | Crank Angle Sensor |
| 12 | All | Airflow Meter |
| 13 | All | Coolant Temperature Sensor |
| 21 | All | Ignition Signal |
| 22 | Pulsar & Sentra | Idle Speed Control |
| 22 | All Except Pulsar & Sentra | Fuel Pump |
| 33 | Pulsar NX, Sentra & Van | Exhaust Gas Sensor |
| 34 | 300 ZX Turbo | Denotation Sensor |
| 41 | (1) | Fuel Temperature Sensor |
| 42 | Pulsar & Van | Throttle Sensor Circuit |
| 43 | Van | Injector Circuit |
| 43 | Pulsar & Sentra | (3) |
| 44 | (2) | (2) |
| (1) On Maxima, 200SX and 300ZX models, code 41 is fuel temperature sensor circuit. On Pulsar, Stanza, Stanza Wagon and Sentra code 41 is the air temperature sensor circuit. (2) On Maxima, 200SX, 300ZX models, fuel temperature sensor circuit is okay. On Van models, injector circuit is okay. On Pulsar and Sentra models, mixture ratio feedback control circuit is okay. (3) Mixture ratio feedback is slipping out. | ||
| (1) | On Maxima, 200SX and 300ZX models, code 41 is fuel temperature sensor circuit. On Pulsar, Stanza, Stanza Wagon and Sentra code 41 is the air temperature sensor circuit. |
| (2) | On Maxima, 200SX, 300ZX models, fuel temperature sensor circuit is okay. On Van models, injector circuit is okay. On Pulsar and Sentra models, mixture ratio feedback control circuit is okay. |
| (3) | Mixture ratio feedback is slipping out. |
ECU DIAGNOSTIC CODES CHART
Preparation
- Make sure that the following are in good order: Battery Ignition System Engine oil and coolant levels Fuses E.C.C.S. harness connectors Vacuum hoses Air intake system (oil filler cap, oil level gauge, etc.) Fuel pressure A.I.V. hose Engine compression E.G.R. valve operation Throttle valve
- On A/C equipped models, checks should be carried out while the A/C is OFF.
- On A/T equipped models, when checking idle RPM, ignition timing and mixture ratio, checks should be carried out while shift lever is in "D" position.
- When measuring "CO" percentage, insert probe more than 40cm (15.7") into tail pipe.
| WARNING | When selector lever is shifted to "D" position, apply parking brake and block both front and rear wheels with chocks. Depress brake pedal while racing the engine to prevent forward surge of vehicle. After adjustment has been made, shift the lever to the "N" or "P" position and remove wheel chocks. |
Overall Inspection Sequence Chart. Scheme 39
MEASUREMENT VOLTAGE OR RESISTANCE OF ECU
Disconnect battery ground cable. Disconnect 20 and 16 pin connectors from ECU. Remove pin terminal retainer from 20 and 16 pin connectors to make it easier to insert tester probes. Connect 20 and 16 pin connectors to ECU carefully. Connect battery ground cable. Measure voltage at each terminal by following ECU DRIVEABILITY INSPECTION TABLES below.
| CAUTION | Perform all voltage measurements with the connectors connected. Perform all resistance measurements with the connectors disconnected. Make sure that there is not any bends or breaks on ECU pin terminal before measurements. Do not touch tester probes between terminals 27 and 28, 35 and 36. |
Measurement Voltage or Resistance of ECU. Scheme 40
Maxima, 200SX SE & 300 ZX. Scheme 41
Pathfinder & Pickup (Z24i & VG 30i). Scheme 42
Pulsar NX (E16i) & Sentra (E16i) (1 of 2). Scheme 43
Pulsar NX (E16i) & Sentra (E16i) (2 of 2). Scheme 44
Pulsar NX SE (CA 16E). Scheme 45
Stanza, Stanza Wagon & 200SX XE. Scheme 46
Van. Scheme 47
Diagnostic Table 1, Maxima, 200SX SE & 300ZX. Scheme 48
Diagnostic Table 2, Maxima, 200SX SE & 300ZX (1 of 2). Scheme 49
Diagnostic Table 2, Maxima, 200SX SE & 300ZX (2 of 2). Scheme 50
Pulsar NX (E16i) & Sentra (E16i) (1 of 2). Scheme 51
Pulsar NX (E16i) & Sentra (E16i) (2 of 2). Scheme 52
Pulsar NX SE (CA16E) (1 of 2). Scheme 53
Pulsar NX SE (CA16E) (2 of 2). Scheme 54
Stanza, Stanza Wagon & 200 SX XE (1 of 2). Scheme 55
Stanza, Stanza Wagon & 200 SX XE (2 of 2). Scheme 56
Van (1 of 3). Scheme 57
Van (2 of 3). Scheme 58
Van (3 of 3). Scheme 59
Maxima, 200SX-SE & 300ZX (1 of 4). Scheme 60
Maxima, 200SX-SE & 300ZX (2 of 4). Scheme 61
Maxima, 200SX-SE & 300ZX (3 of 4). Scheme 62
Maxima, 200SX-SE & 300ZX (4 of 4). Scheme 63
Pulsar NX & Sentra (E16i) (1 of 3). Scheme 64
Pulsar NX & Sentra (E16i) (2 of 3). Scheme 65
Pulsar NX & Sentra (E16i) (3 of 3). Scheme 66
Pulsar NX SE (1 of 4). Scheme 67
Pulsar NX SE (2 of 4). Scheme 68
Pulsar NX SE (3 of 4). Scheme 69
Pulsar NX SE (4 of 4). Scheme 70
Stanza, Stanza Wagon & 200SX XE (1 of 4). Scheme 71
Stanza, Stanza Wagon & 200SX XE (2 of 4). Scheme 72
Stanza, Stanza Wagon & 200SX XE (3 of 4). Scheme 73
Stanza, Stanza Wagon & 200SX XE (4 of 4). Scheme 74
Test A, Maxima, Van, 200SX SE & 300ZX. Scheme 75
Test A, Pulsar NX, Sentra (E16i), Stanza, Wagon & 200SX XE. Scheme 76
Test A, Pulsar NX SE. Scheme 77
Test B, Maxima, Pathfinder, Pickup (VG30i), 200SX-SE & 300ZX. Scheme 78
Test B, Pathfinder/Pickup (Z24i). Scheme 79
Test B, Pulsar NX & Sentra (E16i). Scheme 80
Test B, Pulsar NX SE. Scheme 81
Test B, Stanza, Stanza Wagon & 200SX XE. Scheme 82
Test C, Van. Scheme 83
Test C, Maxima, 200SX-SE & 300ZX. Scheme 84
Test C, Pulsar Nx & Sentra (E16i). Scheme 85
Test C, Pulsar NX SE. Scheme 86
Test C, Stanza, Stanza Wagon & 200 SX XE. Scheme 87
Test D, Maxima, 200SX-SE & 300ZX. Scheme 88
Test E, Van. Scheme 89
Test D, Pulsar NX & Sentra (E16i). Scheme 90
Test D, Pulsar NX SE (1 of 2). Scheme 91
Test D, Pulsar NX SE (2 of 2). Scheme 92
Test D, Stanza, Stanza Wagon & 200SX XE. Scheme 93
Test E, Maxima. Scheme 94
Test E, Stanza, Stanza Wagon & 200SX XE. Scheme 95
Test F, 200SX-SE & 300ZX. Scheme 96
Test E, Pulsar NX & Sentra (E16i). Scheme 97
Test F, Pulsar NX & Sentra (E16i). Scheme 98
Test H, 300ZX. Scheme 99
Test G, Pulsar NX & Sentra (E16i). Scheme 100
Test F, Stanza Wagon. Scheme 101
Test J, Maxima, 200SX-SE & 300ZX. Scheme 102
Test F, Throttle Sensor (1 of 2). Scheme 103
Test F, Throttle Sensor (2 of 2). Scheme 104
Test H, Pulsar NX & Sentra (E16i). Scheme 105
Test G, Van. Scheme 106
Test P, Van. Scheme 107
Test F, Pulsar NX SE. Scheme 108
Test Q, Pulsar NX & Sentra (E16i). Scheme 109
Test X, Maxima, 200SX-SE & 300ZX. Scheme 110
Test R, Pulsar NX & Sentra (E16i). Scheme 111
Test H, Van. Scheme 112
Test I, Pulsar NX & Sentra (E16i). Scheme 113
Test L, Pulsar NX & Sentra (E16i). Scheme 114
Test M, Pulsar NX SE. Scheme 115
Test L, Stanza, Stanza Wagon & 200SX XE. Scheme 116
Test Q, 200SX-SE & 300ZX. Scheme 117
Test EE, Maxima, 200SX-SE & 300 ZX. Scheme 118
Test Q, Stanza, Stanza Wagon & 200SX XE. Scheme 119
Test Q, Pulsar NX SE. Scheme 120
Test R, Van. Scheme 121
Test E, Pulsar NX SE. Scheme 122
Test U, Pulsar NX & Sentra (E16i). Scheme 123
Test U, Pulsar NX & Sentra (E16i) - EFI Relay. Scheme 124
Test U, Stanza, Stanza Wagon & 200SX XE. Scheme 125
Test R, Maxima, 200SX-SE & 300ZX. Scheme 126
Test Test G, Pulsar NX SE. Scheme 127
Test G, Stanza, Stanza Wagon & 200SX XE. Scheme 128
Test M, Maxima, 200 SX SE & 300ZX. Scheme 129
Test J, Pulsar NX & Sentra (E16i). Scheme 130
Test J, Van. Scheme 131
Test H, Pulsar NX SE. Scheme 132
Test H, Stanza, Stanza Wagon & 200SX XE. Scheme 133
Test N, Maxima, 200SX-SE & 300ZX. Scheme 134
Test O, Maxima, 200SX-SE & 300ZX. Scheme 135
Test I, Pulsar NX SE. Scheme 136
Test K, Pulsar NX & Sentra (E16i). Scheme 137
Test I, Stanza, Stanza Wagon & 200SX XE. Scheme 138
Test K, Van. Scheme 139
Test J, Pulsar NX SE. Scheme 140
Test J, Stanza, Stanza Wagon & 200SX XE. Scheme 141
Test Y, 300ZX. Scheme 142
Test K, Pulsar NX SE. Scheme 143
Test L, Van. Scheme 144
Test CC, Maxima, 200SX-SE & 300ZX. Scheme 145
Test L, Pulsar NX SE. Scheme 146
Test K, Stanza, Stanza Wagon & 200SX XE. Scheme 147
Test Z, Maxima, 200SX-SE & 300ZX. Scheme 148
Test N, Pulsar NX & Sentra (E16i). Scheme 149
Test R, Pulsar NX SE. Scheme 150
Test T, Stanza, Stanza Wagon & 200SX XE. Scheme 151
Test M, Pulsar NX & Sentra (E16i). Scheme 152
Test P, Maxima, 200SX-SE, 300ZX, 200SX-SE & 300ZX. Scheme 153
Test X, Van. Scheme 154
Test N, Pulsar NX SE. Scheme 155
Test M, Stanza, Stanza Wagon & 200SX XE. Scheme 156
Test P, 300ZX. Scheme 157
Test N, Van. Scheme 158
Test O, Pulsar NX & Sentra (E16i). Scheme 159
Test P, Pulsar NX & Sentra (E16i). Scheme 160
Test W, Van. Scheme 161
Stanza, Stanza Wagon & 200SX XE. Scheme 162
Test T, Maxima, 200SX-SE & 300ZX. Scheme 163
Test O, Pulsar NX SE. Scheme 164
Test O, Stanza, Stanza Wagon & 200SX XE. Scheme 165
Test U, Maxima, 200SX-SE & 300ZX. Scheme 166
Test U, Van. Scheme 167
Test P, Pulsar NX SE. Scheme 168
Test P, Stanza, Stanza Wagon & 200SX XE. Scheme 169
Test R, Stanza & 200SX XE. Scheme 170
Test S, Stanza & 200SX XE. Scheme 171
Test S, Maxima, 200SX-SE & 300ZX. Scheme 172
Test S, Pulsar NX SE. Scheme 173
Test S, Pulsar NX & Sentra (E16i). Scheme 174
Test T, Van. Scheme 175
Test T, Pulsar NX & Sentra (E16i). Scheme 176
Test T, Pulsar NX SE. Scheme 177
Test V, Stanza, Stanza Wagon & 200SX XE. Scheme 178
Test V, Maxima, 200SX-SE & 300ZX. Scheme 179
Test V, Van. Scheme 180
Operation
The injector cooling fan operates to cool down the temperature of fuel inside the injector and the fuel gallery when engine is stopped under high temperature condition.
Injector Cooling Fan Schematic. Scheme 181
Injector Cooling Fan Flow Chart. Scheme 182
Injector Cooling Fan Operational Chart. Scheme 183
Fan Motor
- Make sure that continuity exists between terminals of fan motor.
- Apply battery voltage to the terminals of fan motor. If fan motor does not operate, replace.
Fan Motor Timer Unit
Check the timer unit with a battery source and a bulb (12V-3W), following the procedure below.
Fan Motor Timer Unit Check. Scheme 184
- Connect terminal 6 to negative terminal of power source, terminal 5 to test lamp terminal and the other test lamp terminal to negative terminal of the power source.
- Connect terminal 1 to positive terminal of power source. If test lamp does not glow then it is OK. If test lamp glows then go to step 3.
- Connect terminal 2 to positive terminal of power source and disconnect it. (Operate timer)
- Connect terminal 9 to negative terminal of power source. If test lamp glows then it is OK. If test lamp does not glow then go to step 5.
- Make sure that test lamp should remain on for about 17 minutes after step 3 is performed, and then go out.
- While test lamp is on, connect terminal 2 to positive terminal of power source. If test lamp goes out then it is OK. If it doesn't go out then it is not OK.
Water Temperature Switch
- Remove water temperature switch
- Check water temperature switch for proper operation.
Operating Temperature
- OFF -- ON 100° (212°F).
