2001 NISSAN ALMERA check engine

12 CHECK ECM POWER SUPPLY CIRCUIT-IV
1. Disconnect ECM relay. (For ECM relay location, refer to ªEngine Control Compartment Parts Locationº.)
2. Check voltage between ECM relay terminal 3 or 5 (only ECM relay in relay box) and ground with CONSULT-II or tester.
YEC048A
OK or NG
OK©GO TO 14.
NG©GO TO 13.
13 DETECT MALFUNCTIONING PART
Check the following.
+Harness connectors E75, F36 (If so equipped)
+Harness for open or short between ECM relay and 10A fuse
©Repair open circuit or short to ground or short to power in harness or connectors.
14 CHECK HARNESS CONTINUITY BETWEEN ECM RELAY AND ECM FOR OPEN AND SHORT
1. Check harness continuity between ECM terminals 110, 112 and ECM relay terminal 5 or 3 (only ECM relay in relay
box).
Refer to WIRING DIAGRAM.
Continuity should exist.
2. Also check harness for short to ground and short to power.
OK or NG
OK©GO TO 16.
NG©GO TO 15.
15 DETECT MALFUNCTIONING PART
Check the following.
+Joint connector-4 (If so equipped)
+Joint connector-6 (If so equipped)
+Harness connector E75, F36 (If so equipped)
+Harness for open or short between ECM and ECM relay
©Repair open circuit or short to ground or short to power in harness or connectors.
TROUBLE DIAGNOSIS FOR POWER SUPPLYQG
Main Power Supply and Ground Circuit (Cont'd)
EC-185

16 CHECK ECM RELAY
1. Apply 12V direct current between ECM relay terminals 1 and 2.
2. Check continuity between relay terminals 3 and 5, 6 and 7.
SEF296X
OK or NG
OK©GO TO 17.
NG©Replace ECM relay.
17 CHECK ECM GROUND CIRCUIT FOR OPEN AND SHORT-II
1. Turn ignition switch ªOFFº.
2. Disconnect ECM harness connector.
3. Check harness continuity between ECM terminals 48, 57, 106, 108 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 18.
NG©Repair open circuit or short to ground or short to power in harness or connectors.
18 CHECK INTERMITTENT INCIDENT
Refer to ªTROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENTº, EC-177.
©INSPECTION END
TROUBLE DIAGNOSIS FOR POWER SUPPLYQG
Main Power Supply and Ground Circuit (Cont'd)
EC-186

SEF987W
Component DescriptionNJEC0050The 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
NJEC0051Specification data are reference values.
MONITOR ITEM CONDITION SPECIFICATION
MAS A/F SE-B1+Engine: After warming up
+Air conditioner switch: ªOFFº
+Shift lever: ªNº
+No-loadIdle 1.0 - 1.7V
2,500 rpm 1.5 - 2.1V
MASS AIRFLOW+Engine: After warming up
+Air conditioner switch: ªOFFº
+Shift lever: ªNº
+No-loadIdle 1.0 - 4.0 g´m/s
2,500 rpm 5.0 - 10.0 g´m/s
ECM Terminals and Reference ValueNJEC0052Specification 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)
61 G Mass air flow sensor[Engine is running]
+Warm-up condition
+Idle speed1.0 - 1.7V
[Engine is running]
+Warm-up condition
+Engine speed is 2,500 rpm1.5 - 2.1V
73 BMass air flow sensor
ground[Engine is running]
+Warm-up condition
+Idle speedApproximately 0V
On Board Diagnosis LogicNJEC0053
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.+Harness or connectors
(The sensor circuit is open or shorted.)
+Mass air flow sensor
B) An excessively low voltage from the sensor is sent
to ECM* when engine is running.+Harness or connectors
(The sensor circuit is open or shorted.)
+Intake air leaks
+Mass air flow sensor
*: When this malfunction is detected, the ECM enters fail-safe mode and the MI lights up.
DTC P0100 MASS AIR FLOW SENSOR (MAFS)QG
Component Description
EC-187

Diagnostic ProcedureNJEC0057
1 INSPECTION START
Which malfunction (A, or B) is duplicated?
Malfunction A or B
A©GO TO 3.
B©GO TO 2.
2 CHECK INTAKE SYSTEM
Check the following for connection.
+Air duct
+Vacuum hoses
+Intake air passage between air duct to collector
OK or NG
OK©GO TO 3.
NG©Reconnect the parts.
3 RETIGHTEN GROUND SCREWS
1. Turn ignition switch ªOFFº.
2. Loosen and retighten engine ground screws.
JEF104Y
©GO TO 4.
DTC P0100 MASS AIR FLOW SENSOR (MAFS)QG
Diagnostic Procedure
EC-191

7 CHECK INPUT SIGNAL CIRCUIT
1. Check harness continuity between mass air flow sensor harness connector terminal 1 and ECM terminal 61.
Refer to wiring diagram.
Continuity should exist.
2. Also check harness for short to ground and short to power.
OK or NG
OK©GO TO 8.
NG©Repair open circuit or short to ground or short to power in harness or connectors.
8 CHECK MASS AIR FLOW SENSOR
Refer to ªComponent Inspectionº, EC-193.
OK or NG
OK©GO TO 9.
NG©Replace mass air flow sensor.
9 CHECK INTERMITTENT INCIDENT
Perform ªTROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENTº, EC-177.
©INSPECTION END
SEF993W
SEF987W
Component InspectionNJEC0058MASS AIR FLOW SENSORNJEC0058S011. Turn ignition switch ªONº.
2. Start engine and warm it up to normal operating temperature.
3. Check voltage between ECM terminal 61 (Mass air flow sen-
sor signal) and ground.
Conditions Voltage V
Ignition switch ªONº (Engine stopped.) Less than 1.2
Idle (Engine is warmed-up to normal operating
temperature.)1.0 - 1.7
2,500 rpm (Engine is warmed-up to normal oper-
ating temperature.)1.7 - 2.1
Idle to about 4,000 rpm* 1.0 - 1.7 to Approx. 4.0
*: Check for linear voltage rise in response to increases to about 4,000 rpm in
engine speed.
4. If the voltage is out of specification, disconnect mass air flow
sensor harness connector and connect it again. Repeat above
check.
5. If NG, remove mass air flow sensor from air duct. Check hot
film for damage or dust.
DTC P0100 MASS AIR FLOW SENSOR (MAFS)QG
Diagnostic Procedure (Cont'd)
EC-193

2 CHECK POWER SUPPLY (Models with intake air temperature sensor in mass air flow sensor)
1. Turn ignition switch ªOFFº.
2. Disconnect mass air flow sensor harness connector.
JEF105Y
3. Turn ignition switch ªONº.
4. Check voltage between terminal 5 and ground with CONSULT-II or tester.
SEC503C
OK or NG
OK©GO TO 4.
NG©GO TO 3.
3 DETECT MALFUNCTIONING PART
Check the following.
+Harness connectors E74, F35 (If so equipped)
+Harness for open or short between ECM and intake air temperature sensor
©Repair harness or connectors.
4 CHECK GROUND CIRCUIT
1. Turn ignition switch ªOFFº.
2. Check harness continuity between intake air temperature sensor harness connector terminal 2 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 6.
NG©GO TO 5.
DTC P0110 INTAKE AIR TEMPERATURE SENSORQG
Diagnostic Procedure (Cont'd)
EC-199

SEF594K
Component DescriptionNJEC0072The 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 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 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.
CONSULT-II Reference Value in Data Monitor
Mode
NJEC0073
MONITOR ITEM CONDITION SPECIFICATION
COOLAN TEMP/S+Engine: After warming up More than 70ÉC (158ÉF)
On Board Diagnosis LogicNJEC0074
DTC No. Malfunction is detected when ... Check Items (Possible Cause)
P0115
0115+An excessively high or low voltage from the sensor is
sent to ECM.*+Harness or connectors
(The sensor circuit is open or shorted.)
+Engine coolant temperature sensor
*: When this malfunction is detected, the ECM enters fail-safe mode and the MI lights up.
DTC P0115 ENGINE COOLANT TEMPERATURE SENSOR
(ECTS) (CIRCUIT)
QG
Component Description
EC-201

Diagnostic ProcedureNJEC0077
1 CHECK POWER SUPPLY
1. Turn ignition switch ªOFFº.
2. Disconnect engine coolant temperature sensor harness connector.
SEF999W
3. Turn ignition switch ªONº.
4. Check voltage between terminal 1 and ground with CONSULT-II or tester.
SEF301X
OK or NG
OK©GO TO 3.
NG©GO TO 2.
2 DETECT MALFUNCTIONING PART
Check the harness for open or short between ECM and engine coolant temperature sensor.
©Repair harness or connectors.
3 CHECK GROUND CIRCUIT
1. Turn ignition switch ªOFFº.
2. Check harness continuity between engine coolant temperature sensor harness connector terminal 2 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 5.
NG©GO TO 4.
DTC P0115 ENGINE COOLANT TEMPERATURE SENSOR
(ECTS) (CIRCUIT)
QG
Diagnostic Procedure
EC-205