2001 NISSAN ALMERA check engine

SEF987W
Component DescriptionNJEC0642The mass air flow sensor (MAFS) is placed in the stream of intake
air. It measures the intake air flow rate by measuring a part of the
entire intake air flow. It consists of a hot film that is supplied with
electric current from the ECM. The temperature of the hot film is
controlled by the ECM a certain amount. The heat generated by the
hot film 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 film as air flow increases. The ECM
detects the air flow by means of this current change.
CONSULT-II Reference Value in Data Monitor
Mode
NJEC0643Specification data are reference values.
MONITOR ITEM CONDITION SPECIFICATION
MAS AIR/FL SE+Engine: After warming up
+Air conditioner switch: ªOFFº
+Shift lever: Neutral position
+No-loadIdle 1.5 - 2.0V
ECM Terminals and Reference ValueNJEC0644Specification data are reference values, and are measured between each terminal and ground.
CAUTION:
Do not use ECM ground terminals when measuring input/output voltage. Doing so may result in dam-
age to the ECM's transistor. Use a ground other than ECM terminals, such as the ground.
TER-
MINAL
NO.WIRE
COLORITEM CONDITION DATA (DC Voltage)
218 B Sensor's ground[Engine is running]
+Warm-up condition
+Idle speedApproximately 0V
223 WMass air flow sensor
power supply[Ignition switch ªONº]Approximately 5V
224 R Mass air flow sensor[Engine is running]
+Warm-up condition
+Idle speed1.5 - 2.0V
On Board Diagnosis LogicNJEC0645
DTC Malfunction is detected when ... Check Items (Possible Cause)
P0100
0102+An excessively high or low voltage from the sen-
sor is sent to ECM.+Harness or connectors
(The sensor circuit is open or shorted.)
+Mass air flow sensor
SEF817Y
DTC Confirmation ProcedureNJEC0646WITH CONSULT-IINJEC0646S011) Turn ignition switch ªONº, and wait at least 6 seconds.
2) Select ªDATA MONITORº mode with CONSULT-II.
3) Start engine and wait at least 3 seconds.
4) If DTC is detected, go to ªDiagnostic Procedureº, EC-677.
WITHOUT CONSULT-IINJEC0646S021) Turn ignition switch ªONº, and wait at least 6 seconds.
2) Start engine and wait at least 3 seconds.
DTC P0100 MASS AIR FLOW SENYD
Component Description
EC-673

Diagnostic ProcedureNJEC0648
1 CHECK MAFS POWER SUPPLY CIRCUIT
1. Turn ignition switch ªOFFº.
2. Disconnect mass air flow sensor harness connector.
SEF884Y
3. Turn ignition switch ªONº.
4. Check voltage between mass air flow sensor terminals 2, 4 and ground with CONSULT-II or tester.
SEF297X
OK or NG
OK©GO TO 3.
NG©GO TO 2.
2 DETECT MALFUNCTIONING PART
Check the following.
+Harness connectors E75, F36 (Sedan models and hatchback models with ecm in engine compartment)
+Harness for open or short between mass air flow sensor and ECM
+Harness for open or short between mass air flow sensor and ECM relay
©Repair open circuit or short to ground or short to power in harness or connector.
DTC P0100 MASS AIR FLOW SENYD
Diagnostic Procedure
EC-677

3 CHECK MAFS GROUND CIRCUIT FOR OPEN AND SHORT
1. Turn ignition switch ªOFFº.
2. Loosen and retighten engine ground screws.
SEF380Y
3. Check harness continuity between mass air flow sensor terminal 3 and engine ground. Refer to Wiring Diagram.
Continuity should exist.
4. Also check harness for short to ground and short to power.
OK or NG
OK©GO TO 5.
NG©GO TO 4.
4 DETECT MALFUNCTIONING PART
Check harness for open or short between mass air flow sensor and ECM.
©Repair open circuit or short to ground or short to power in harness or connectors.
5 CHECK MAFS INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
1. Disconnect ECM harness connector.
2. Check harness continuity between mass air flow sensor terminal 1 and ECM terminal 224. Refer to Wiring Diagram.
Continuity should exist.
3. Also check harness for short to ground and short to power.
OK or NG
OK©GO TO 6.
NG©Repair open circuit or short to ground or short to power in harness or connectors.
DTC P0100 MASS AIR FLOW SENYD
Diagnostic Procedure (Cont'd)
EC-678

6 CHECK MASS AIR FLOW SENSOR
1. Reconnect harness connectors disconnected.
2. Start engine and warm it up to normal operating temperature.
3. Check voltage between ECM terminal 224 (Mass air flow sensor signal) and ground.
SEF441Z
4. If the voltage is out of specification, disconnect MAFS harness connector and connect it again.
Then repeat above check.
OK or NG
OK©GO TO 7.
NG©Replace mass air flow sensor.
7 CHECK INTERMITTENT INCIDENT
Refer to ªTROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENTº, EC-665.
©INSPECTION END
DTC P0100 MASS AIR FLOW SENYD
Diagnostic Procedure (Cont'd)
EC-679

SEF594K
DescriptionNJEC0649The 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.
SEF012P

Engine coolant tempera-
ture ÉC (ÉF)Voltage* (V) Resistance (kW)
þ10 (14) 4.4 7.0 - 11.4
20 (68) 3.5 2.1 - 2.9
50 (122) 2.3 0.68 - 1.00
90 (194) 1.0 0.236 - 0.260
*: These data are reference values and measured between ECM terminal 347
(Engine coolant temperature sensor) and ground.
CAUTION:
Do not use ECM ground terminals when measuring input/
output voltage. Doing so may result in damage to the ECM's
transistor. Use a ground other than ECM terminals, such as
the ground.
On Board Diagnosis LogicNJEC0650
DTC Malfunction is detected when ... Check Items (Possible Cause)
P0115
0103+An excessively high or low voltage from the sen-
sor is entered to ECM.+Harness or connectors (The sensor circuit is
open or shorted.)
+Engine coolant temperature sensor
SEF817Y
DTC Confirmation ProcedureNJEC0651WITH CONSULT-IINJEC0651S011) Turn ignition switch ªONº.
2) Select ªDATA MONITORº mode with CONSULT-II.
3) Wait at least 5 seconds.
4) If DTC is detected, go to ªDiagnostic Procedureº, EC-683.
WITHOUT CONSULT-IINJEC0651S021) Turn ignition switch ªONº and wait at least 5 seconds.
2) Turn ignition switch ªOFFº, wait at least 5 seconds and then
turn ªONº.
DTC P0115 COOLANT TEMP SENYD
Description
EC-680

Diagnostic ProcedureNJEC0653
1 CHECK ECTS POWER SUPPLY CIRCUIT
1. Turn ignition switch ªOFFº.
2. Disconnect engine coolant temperature sensor harness connector.
SEF382Y
3. Turn ignition switch ªONº.
4. Check voltage between ECTS terminal 2 and ground with CONSULT-II or tester.
SEF401Y
OK or NG
OK©GO TO 2.
NG©Repair open circuit or short to ground or short to power in harness or connectors.
2 CHECK ECTS GROUND CIRCUIT FOR OPEN AND SHORT
1. Turn ignition switch ªOFFº.
2. Check harness continuity between ECTS terminal 1 and engine ground. Refer to Wiring Diagram.
Continuity should exist.
3. Also check harness for short to ground and short to power.
OK or NG
OK©GO TO 4.
NG©GO TO 3.
3 DETECT MALFUNCTIONING PART
Check the following harness for open or short between ECM and engine coolant temperature sensor.
©Repair open circuit or short to ground or short to power in harness or connectors.
DTC P0115 COOLANT TEMP SENYD
Diagnostic Procedure
EC-683

4 CHECK ENGINE COOLANT TEMPERATURE SENSOR
1. Remove engine coolant temperature sensor from the engine.
2. Check resistance between ECTS terminals 1 and 2 as shown in the figure.
SEF304X
OK or NG
OK©GO TO 5.
NG©Replace engine coolant temperature sensor.
5 CHECK INTERMITTENT INCIDENT
Refer to ªTROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENTº, EC-665.
©INSPECTION END
DTC P0115 COOLANT TEMP SENYD
Diagnostic Procedure (Cont'd)
EC-684

5 CHECK ACCELERATOR POSITION SENSOR GROUND CIRCUIT FOR OPEN AND SHORT
1. Turn ignition switch ªOFFº.
2. Loosen and retighten engine ground screw.
SEF380Y
3. Check harness continuity between accelerator work unit terminal 4 and engine ground. Refer to Wiring Diagram.
Continuity should exist.
4. Also check harness for short to ground and short to power.
OK or NG
OK©GO TO 7.
NG©GO TO 6.
6 DETECT MALFUNCTIONING PART
Check the following.
+Harness connectors F112, M74 or F103, M64
+Harness for open or short between ECM and accelerator work unit
©Repair open circuit or short to ground or short to power in harness or connectors.
7 CHECK ACCELERATOR POSITION SENSOR INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
1. Disconnect ECM harness connector.
2. Check harness continuity between ECM terminal 434 and accelerator work unit terminal 2. Refer to Wiring Diagram.
Continuity should exist.
3. Also check harness for short to ground and short to power.
OK or NG
OK©GO TO 9.
NG©GO TO 8.
8 DETECT MALFUNCTIONING PART
Check the following.
+Harness connectors F112, M74 or F103, M64
+Harness for open or short between ECM and accelerator work unit
©Repair open circuit or short to ground or short to power in harness or connectors.
DTC P0120 ACCEL POS SENSORYD
Diagnostic Procedure (Cont'd)
EC-691