Basic InspectionNCEC0038Precaution:
Perform Basic Inspection without electrical or mechanical loads applied;
IHeadlamp switch is OFF,
IOn vehicles equipped with daytime running light systems, set lighting switch to the 1st position to light only
small lamps.
IAir conditioner switch is OFF,
IRear window defogger switch is OFF,
ISteering wheel is in the straight-ahead position, etc.
1 INSPECTION START
1. Check service records for any recent repairs that may indicate a related problem, or the current need for scheduled maintenance.
2. Open engine hood and check the following:
IHarness connectors for improper connections
IVacuum hoses for splits, kinks, or improper connections
IWiring for improper connections, pinches, or cuts
IAir cleaner clogging
IHoses and ducts for leaks
SEF983U
©GO TO 2.
2 CHECK THROTTLE DRUM OPERATION
Confirm that throttle drum is in contact with stopper.
OK or NG
OK (With CONSULT-II)©GO TO 5.
OK (Without CONSULT-II)©GO TO 8.
NG©GO TO 3.
3 CHECK ACCELERATOR WIRE INSTALLATION
Check accelerator wire for slack.
OK or NG
OK©GO TO 4.
NG©Adjust accelerator wire. Refer to FE-section, ªAdjusting Accelerator Wireº.
4 CHECK THROTTLE VALVE OPERATION
1. Remove intake air ducts.
2. Check throttle valve operation when moving throttle drum by hand.
OK or NG
OK©Retighten the throttle drum fixing nuts.
NG©Clean the throttle body and throttle valve.
TROUBLE DIAGNOSIS Ð BASIC INSPECTIONSR20DE
Basic Inspection
EC-84
18 CHECK TARGET IDLE SPEED AGAIN
With CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Select ªENG SPEEDº in ªDATA MONITORº mode with CONSULT-II.
3. Check idle speed.
750 50 rpm
Without CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Check idle speed.
750 50 rpm
OK or NG
OK©GO TO 20.
NG©GO TO 19.
19 CHECK ECM FUNCTION
1. Substitute another known-good ECM to check ECM function. (ECM may be the cause of a problem, but this is rarely the case.)
2. Perform initialization of NATS system and registration of NATS ignition key IDs. Refer to ªNATS (Nissan Anti-Theft System)º, EC-SR-
58.
©GO TO 14.
20 CHECK IGNITION TIMING
1. Start engine and warm it up to normal operating temperature.
2. Check ignition timing at idle using a timing light.
SEF984UIgnition timing:
15É 2É BTDC
OK or NG
OK©GO TO 28.
NG©GO TO 21.
21 CHECK TIMING CHAIN INSTALLATION
Check timing chain installation. Refer to EM-section.
OK or NG
OK©GO TO 19.
NG©1. Repair the timing chain installation.
2. GO TO 14.
Timing light
TROUBLE DIAGNOSIS Ð BASIC INSPECTIONSR20DE
Basic Inspection (Cont'd)
EC-89
22 CHECK IGNITION TIMING
1. Start engine and let it idle.
2. Check ignition timing at idle using a timing light.
SEF984UIgnition timing:
15É 2É BTDC
OK or NG
OK©GO TO 28.
NG©GO TO 23.
23 PERFORM IDLE AIR VOLUME LEARNING
Refer to ªIdle Air Volume Learningº, EC-SR-46
Which is the result CMPLT or INCMP?
CMPLT or INCMP
CMPLT©GO TO 24.
INCMP©GO TO 23.
24 CHECK TARGET IDLE SPEED AGAIN
With CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Select ªENG SPEEDº in ªDATA MONITORº mode with CONSULT-II.
3. Check idle speed.
750 50 rpm
Without CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Check idle speed.
750 50 rpm
OK or NG
OK©GO TO 26.
NG©GO TO 15.
25 CHECK ECM FUNCTION
1. Substitute another known-good ECM to check ECM function.
(ECM may be the cause of a problem, but this is rarely the case.)
2. Perform initialization of NATS system and registration of NATS ignition key IDs. Refer to ªNATS (Nissan Anti-Theft System)º,
EC-SR-58.
©GO TO 23.
26 CHECK IGNITION TIMING AGAIN
Check ignition timing again. Refer to Test No. 22.
OK or NG
OK©GO TO 28.
NG©GO TO 27.
Timing light
TROUBLE DIAGNOSIS Ð BASIC INSPECTIONSR20DE
Basic Inspection (Cont'd)
EC-90
CONSULT-II Reference Value in Data Monitor
Mode
NCEC0042Remarks:
ISpecification data are reference values.
ISpecification data are output/input values which are detected or supplied by the ECM at the connector.
* Specification data may not be directly related to their components signals/values/operations.
(i.e., Adjust ignition timing with a timing light before monitoring IGN TIMING. Specification data might be displayed even when igni-
tion timing is not adjusted to specification. This IGN TIMING monitors the data calculated by the ECM according to the input signals
from the camshaft position sensor and other ignition timing related sensors.)
IIf the real-time diagnosis results are NG, and the on board diagnostic system results are OK, when diagnosing the mass air flow sensor,
first check to see if the fuel pump control circuit is normal.
MONITOR ITEM CONDITION SPECIFICATION
ENG SPEEDITachometer: Connect
IRun engine and compare tachometer indication with the CONSULT-II
value.Almost the same speed as the
CONSULT-II value.
MAS A/F SE -B1IEngine: After warming up
IAir conditioner switch: OFF
IShift lever: ªNº
INo-loadIdle 1.0 - 1.7V
2,500 rpm 1.5 - 2.4V
COOLAN TEMP/SIEngine: After warming up More than 70ÉC (158ÉF)
HO2S1 (B1)
IEngine: After warming upMaintaining engine speed at 2,000
rpm0 - 0.3V+,0.6 - 1.0V
HO2S1 MNTR (B1)LEAN+,RICH
Changes more than 5 times
during 10 seconds.
HO2S2 (B1)
IEngine: After warming upRevving engine from idle to 3,000
rpm quickly0 - 0.3V+,0.6 - 1.0V
HO2S2 MNTR (B1)LEAN+,RICH
VHCL SPEED SEITurn drive wheels and compare speedometer indication with the CON-
SULT-II valueAlmost the same speed as the
CONSULT-II value
BATTERY VOLTIIgnition switch: ON (Engine stopped) 11 - 14V
THRTL POS SENIEngine is idling Throttle valve fully closed 0.35 - 0.65V
IIgnition switch: ON
(Engine stopped)Throttle valve fully opened 3.5 - 4.5V
START SIGNALIIgnition switch: ON,START,ON OFF,ON,OFF
CLSD THL/P SW
CLSD THL POSIEngine: IdleThrottle valve: Idle position ON
Throttle valve: Slightly open OFF
AIR COND SIGIEngine: After warming up, idle
the engineA/C switch ªOFFº OFF
A/C switch ªONº
(Compressor operates)ON
P/N POSI SWIIgnition switch: ONShift lever ªPº or ªNº ON
Except above OFF
PW/ST SIGNALIEngine: After warming up, idle
the engineSteering wheel in neutral position
(forward direction)OFF
The steering wheel is fully turned ON
IGNITION SWIIgnition switch: ON,OFF ON,OFF
INJ PULSE -B1IEngine: After warming up
IAir conditioner switch: OFF
IShift lever: ªNº
INo-loadIdle 2.4 - 3.2 msec
2,000 rpm 1.9 - 2.8 msec
HEATER FAN SWIIgnition switch: ONHeater fan switch: ON ON
Heater fan switch: OFF OFF
TROUBLE DIAGNOSIS Ð GENERAL DESCRIPTIONSR20DE
CONSULT-II Reference Value in Data Monitor Mode
EC-98
Component DescriptionNCEC0050The mass air flow sensor is placed in the stream of intake air. It
measures the intake flow rate by measuring a part of the entire
intake flow. It consists of a hot wire that is supplied with electric
current from the ECM. The temperature of the hot wire is controlled
by the ECM a certain amount. The heat generated by the hot wire
is reduced as the intake air flows around it. The more air, the
greater the heat loss.
Therefore, the ECM must supply more electric current to maintain
the temperature of the hot wire as air flow increases. The ECM
detects the air flow by means of this current change.
CONSULT-II Reference Value in Data Monitor
Mode
NCEC0051Specification data are reference values.
MONITOR ITEM CONDITION SPECIFICATION
MAS A/F SE -B1IEngine: After warming up
IAir conditioner switch: ªOFFº
IShift lever: ªNº
INo-loadIdle 1.0 - 1.7V
2,500 rpm 1.5 - 2.4V
CAL/LD VALUEIEngine: After warming up
IAir conditioner switch: ªOFFº
IShift lever: ªNº
INo-loadIdle Not used
2,500 rpm Not used
MASS AIRFLOWIEngine: After warming up
IAir conditioner switch: ªOFFº
IShift lever: ªNº
INo-loadIdle 2.5 - 5.0 g×m/s
2,500 rpm 7.1 - 12.5 g×m/s
ECM Terminals and Reference ValueNCEC0052Specification data are reference values and are measured between each terminal and 48 (ECM ground).
TERMI-
NAL
NO.WIRE
COLORITEM CONDITION DATA (DC Voltage)
61 B Mass air flow sensor[Engine is running]
IWarm-up condition
IIdle speed1.3 - 1.7V
[Engine is running]
IWarm-up condition
IEngine speed is 2,500 rpm1.8 - 2.4V
73 WMass air flow sensor
ground[Engine is running]
IWarm-up condition
IIdle speedApproximately 0V
On Board Diagnosis LogicNCEC0053
DTC No. Malfunction is detected when ... Check Items (Possible Cause)
P0100*
0100A) An excessively high voltage from the sensor is sent to
ECM when engine is not running.IHarness or connectors
(The sensor circuit is open or shorted.)
IMass air flow sensor
B) An excessively low voltage from the sensor is sent to
ECM when engine is running.IHarness or connectors
(The sensor circuit is open or shorted.)
IIntake air leaks
IMass air flow sensor
*: When this malfunction is detected, the ECM enters fail-safe mode and the MI lights up.
SEF987W
DTC P0100 MASS AIR FLOW SENSOR (MAFS)SR20DE
Component Description
EC-120
Component DescriptionNCEC0072The engine coolant temperature sensor is used to detect the
engine coolant temperature. The sensor modifies a voltage signal
from the ECM. The modified signal returns to the ECM as the
engine coolant temperature input. The sensor uses a thermistor
which is sensitive to the change in temperature. The electrical
resistance of the thermistor decreases as temperature increases.
Engine coolant temperature
ÉC (ÉF)Voltage*
VResistance
kW
þ10 (14)4.4 7.0 - 11.4
20 (68)3.5 2.1 - 2.9
50 (122)2.2 0.68 - 1.00
90 (194)0.9 0.236 - 0.260
*: These data are reference values and are measured between ECM terminal 70
(Engine coolant temperature sensor) and ECM terminal 48 (ECM ground).
CONSULT-II Reference Value in Data Monitor
Mode
NCEC0073
MONITOR ITEM CONDITION SPECIFICATION
COOLAN TEMP/SIEngine: After warming up More than 70ÉC (158ÉF)
On Board Diagnosis LogicNCEC0074
DTC No. Malfunction is detected when ... Check Items (Possible Cause)
P0115
0115IAn excessively high or low voltage from the sensor is
sent to ECM.*IHarness or connectors
(The sensor circuit is open or shorted.)
IEngine coolant temperature sensor
*: When this malfunction is detected, the ECM enters fail-safe mode and the MI lights up.
Detected items Engine operating condition in fail-safe mode
Engine coolant tempera-
ture sensor circuitEngine coolant temperature will be determined by ECM based on the time after turning ignition switch
ªONº or ªSTARTº.
CONSULT-II displays the engine coolant temperature decided by ECM.
ConditionEngine coolant temperature decided (CONSULT-II
display)
Just as ignition switch is turned ON or Start 40ÉC (104ÉF)
More than approx. 4 minutes after ignition ON or
Start80ÉC (176ÉF)
Except as shown above40 - 80ÉC (104 - 176ÉF)
(Depends on the time)
When the fail-safe system for engine coolant temperature sensor is activated, the cooling fan operates
while the engine is running.
SEF594K
SEF012P
DTC P0115 ENGINE COOLANT TEMPERATURE SENSOR
(ECTS) (CIRCUIT)SR20DE
Component Description
EC-132
ECM Terminals and Reference Value=NCEC0081Specification data are reference values and are measured between each terminal and 48 (ECM ground).
TERMI-
NAL
NO.WIRE
COLORITEM CONDITION DATA (DC Voltage)
58 B Sensors' ground[Engine is running]
IWarm up condition
IIdle speedApproximately 0V
92 Y Throttle position sensor[Engine is running]
IAccelerator pedal fully released0.35 - 0.65V
[Ignition switch ªONº]
IAccelerator pedal fully depressedApproximately 4.0V
111 G Sensors' power supply[Ignition switch ªONº]Approximately 5V
On Board Diagnosis LogicNCEC0082
DTC No. Malfunction is detected when ... Check Items (Possible Cause)
P0120
0120An excessively low or high voltage from the sensor is
sent to ECM while driving*.IHarness or connectors
(The throttle position sensor circuit is open or
shorted.)
IThrottle position sensor
*: When this malfunction is detected, the ECM enters fail-safe mode and the MI lights up.
Detected items Engine operating condition in fail-safe mode
Throttle position sensor
circuitThrottle position will be determined based on the injected fuel amount and the engine speed.
Therefore, acceleration will be poor.
Condition Driving condition
When engine is idling Normal
When accelerating Poor acceleration
DTC Confirmation ProcedureNCEC0083NOTE:
If ªDTC Confirmation Procedureº has been previously conducted,
always turn ignition switch ªOFFº and wait at least 9 seconds
before conducting the next test.
CAUTION:
Always drive vehicle at a safe speed.
TESTING CONDITION:
IBefore performing the following procedure, confirm that
battery voltage is more than 10V at idle.
IThis test may be conducted with the drive wheels lifted in
the shop or by driving the vehicle. If a road test is
expected to be easier, it is unnecessary to lift the vehicle.
DTC P0120 THROTTLE POSITION SENSORSR20DE
ECM Terminals and Reference Value
EC-138
On Board Diagnosis LogicNCEC0188With the Air/Fuel Mixture Ratio Self-Learning Control, the actual mixture ratio can be brought closely to the
theoretical mixture ratio based on the mixture ratio feedback signal from the heated oxygen sensor 1 (front).
The ECM calculates the necessary compensation to correct the offset between the actual and the theoretical
ratios.
In case the amount of the compensation value is extremely large (The actual mixture ratio is too lean.), the
ECM judges the condition as the fuel injection system malfunction and lights up the MI (2 trip detection logic).
Sensor Input Signal to ECMECM func-
tionActuator
Heated oxygen sensor 1 (front)Density of oxygen in exhaust gas
(Mixture ratio feedback signal)Fuel injec-
tion & mix-
ture ratio
controlInjectors
DTC No. Malfunction is detected when ... Check Items (Possible Cause)
P0171
0171IFuel injection system does not operate properly.
IThe amount of mixture ratio compensation is too large.
(The mixture ratio is too lean.)IIntake air leaks
IHeated oxygen sensor 1 (front)
IInjectors
IExhaust gas leaks
IIncorrect fuel pressure
ILack of fuel
IMass air flow sensor
DTC Confirmation ProcedureNCEC0189NOTE:
If ªDTC Confirmation Procedureº has been previously conducted,
always turn ignition switch ªOFFº and wait at least 9 seconds
before conducting the next test.
TESTING CONDITION:
IAlways perform at a temperature above þ10ÉC (14ÉF).
With CONSULT-II
1) Start engine and warm it up to normal operating temperature.
2) Turn ignition switch ªOFFº and wait at least 9 seconds.
3) Turn ignition switch ªONº and select ªSELF-LEARN CON-
TROLº in ªWORK SUPPORTº mode with CONSULT-II.
4) Clear the self-learning control coefficient by touching ªCLEARº.
5) Select ªDATA MONITORº mode with CONSULT-II.
6) Start engine again and let it idle for at least 10 minutes.
The 1st trip DTC P0171 should be detected at this stage, if a
malfunction exists. If so, go to ªDiagnostic Procedureº, EC-SR-
214.
7) If it is difficult to start engine at step 6, the fuel injection sys-
tem has a malfunction.
8) Crank engine while depressing accelerator pedal. If engine
starts, go to ªDiagnostic Procedureº, EC-SR-214. If engine
does not start, visually check for exhaust and intake air leak.
With GST
Follow the procedure ªWith CONSULT-IIº above.
SEF652Y
SEF058Y
SEF203X Mass air flow sensor
harness connector
Air cleaner
DTC P0171 FUEL INJECTION SYSTEM FUNCTION
(LEAN SIDE)SR20DE
On Board Diagnosis Logic
EC-212