1998 NISSAN PATROL sensor

Mass Air Flow Sensor (MAFS)
COMPONENT DESCRIPTION
The mass air ¯ow sensor is placed in the stream of intake air. It
measures the intake air ¯ow rate by measuring a part of the entire
intake air ¯ow. 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 ¯ows around it. The more air, the
greater the heat loss.
Therefore, the ECM must supply more electric current to the hot
wire as air ¯ow increases. This maintains the temperature of the hot
wire. The ECM detects the air ¯ow by means of this current change.
CONSULT REFERENCE VALUE IN DATA MONITOR MODE
Remarks: Speci®cation data are reference values.
MONITOR ITEM CONDITION SPECIFICATION
MAS AIR/FL SE+Engine: After warming up
+Air conditioner switch: ``OFF''
+Shift lever: ``N''
+No-loadIdle 1.6 - 2.0V
ECM TERMINALS AND REFERENCE VALUE
Remarks: Speci®cation data are reference values, and are measured between each terminal andV43(ECCS
ground) with a voltmeter.
TER-
MINAL
NO.WIRE
COLORITEM CONDITIONDATA
(DC voltage)
35 R Mass air ¯ow sensorEngine is running.
(Warm-up condition)
Idle speed1.6 - 2.0V
50 B Sensors' groundEngine is running.
(Warm-up condition)
Idle speedApproximately 0V
ON BOARD DIAGNOSIS LOGIC
Diagnostic
Trouble
Code No.Malfunction is detected when ...Check Items
(Possible Cause)
12+An excessively high or low voltage from the sensor is
sent to ECM.+Harness or connectors
(The sensor circuit is open or shorted.)
+Mass air ¯ow sensor
SEF734V
TROUBLE DIAGNOSIS FOR ``MASS AIR FLOW SEN'' (DTC 12)
EC-74

DIAGNOSTIC TROUBLE CODE CONFIRMATION
PROCEDURE
1) Turn ignition switch ``ON'', and wait at least 6 seconds.
2) Select ``DATA MONITOR'' mode with CONSULT.
3) Start engine and wait at least 3 seconds.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------OR-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
1) Turn ignition switch ``ON'', and wait at least 6 seconds.
2) Start engine and wait at least 3 seconds.
3) Turn ignition switch ``OFF'', wait at least 5 seconds and
then turn ``ON''.
4) Perform ``Diagnostic Test Mode II (Self-diagnostic
results)'' with ECM.
SEF735V
TROUBLE DIAGNOSIS FOR ``MASS AIR FLOW SEN'' (DTC 12)
Mass Air Flow Sensor (MAFS) (Cont'd)
EC-75

TEC424
TROUBLE DIAGNOSIS FOR ``MASS AIR FLOW SEN'' (DTC 12)
Mass Air Flow Sensor (MAFS) (Cont'd)
EC-76

DIAGNOSTIC PROCEDURE
INSPECTION START
CHECK POWER SUPPLY.
1. Turn ignition switch ``OFF''.
2. Disconnect mass air ¯ow sensor har-
ness connector.
3. Turn ignition switch ``ON''.
4. Check voltage between terminal
V1and ground with CONSULT or tester.
Voltage: Battery voltage
OK
cNG
Check the following.
+Harness connectors
M52,F7+Harness for open or
short between mass air
¯ow sensor and ECM
+Harness for open or
short between mass air
¯ow sensor and ECCS
relay
If NG, repair harness or
connector.
CHECK GROUND CIRCUIT.
1. Turn ignition switch ``OFF''.
2. Loosen and retighten engine ground
screws.
3. Check harness continuity between ter-
minal
V2and engine ground.
Continuity should exist.
If OK, check harness for short to
ground and short to power.
OK
cNG
Check the following.
+Harness connectors
E106,M88+Harness connectorsM51,F6+Harness for open or
short between mass air
¯ow sensor and ECM
+Harness for open or
short between mass air
¯ow sensor and TCM
If NG, repair open circuit or
short to ground or short to
power in harness or con-
nectors.
CHECK INPUT SIGNAL CIRCUIT.
1. Disconnect ECM harness connector.
2. Check harness continuity between ter-
minal
V3and ECM terminalV35.
Continuity should exist.
If OK, check harness for short to
ground and short to power.
OK
cNG
Repair open circuit or short
to ground or short to power
in harness or connectors.
CHECK COMPONENT
(Mass air ¯ow sensor).
Refer to ``COMPONENT INSPECTION''
on next page.
OK
cNG
Replace mass air ¯ow sen-
sor.
Disconnect and reconnect harness con-
nectors in the circuits. Then retest.
Trouble is not ®xed.
Check ECM pin terminals for damage and
check the connection of ECM harness
connector. Reconnect ECM harness con-
nector and retest.
INSPECTION END
SEF713V
SEF736V
SEF676V
SEF737V
SEF738V
.
.
.
.
.
.
.
TROUBLE DIAGNOSIS FOR ``MASS AIR FLOW SEN'' (DTC 12)
Mass Air Flow Sensor (MAFS) (Cont'd)
EC-77

COMPONENT INSPECTION
Mass air ¯ow sensor
1. Start engine and warm it up to normal operating temperature.
2. Check voltage between ECM terminal
V35and ground under the
following condition.
Conditions Voltage V
Ignition switch ``ON'' (Engine stopped.) Less than 1.0
Idle (Engine is warmed-up sufficiently.) 1.0 - 1.7
2,500 rpm Approximately 2.1
Idle to about 4,000 rpm* 1.0 - 1.7 to Approx. 4.0
*: Check for linear voltage rise in response to increase to about 4,000 rpm in engine
speed.
3. If NG, remove mass air ¯ow sensor from air duct. Check hot
wire for damage and dust.
SEF739V
SEF740V
TROUBLE DIAGNOSIS FOR ``MASS AIR FLOW SEN'' (DTC 12)
Mass Air Flow Sensor (MAFS) (Cont'd)
EC-78

Engine Coolant Temperature (ECT) Sensor
The engine coolant temperature sensor is used to detect the engine
coolant temperature. The sensor modi®es a voltage signal from the
ECM. The modi®ed signal returns to the ECM as the engine cool-
ant temperature input. The sensor uses a thermistor which is sen-
sitive to the change in temperature. The electrical resistance of the
thermistor decreases as temperature increases.

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
V19(Engine coolant temperature sensor) and ECM terminalV43(ECCS ground).
Diagnostic
Trouble Code
No.Malfunction is detected when ...Check Items
(Possible Cause)
13+An excessively high or low voltage from the sensor is
entered to ECM.+Harness or connectors
(The sensor circuit is open or shorted.)
+Engine coolant temperature sensor
DIAGNOSTIC TROUBLE CODE CONFIRMATION
PROCEDURE
1) Turn ignition switch ``ON''.
2) Select ``DATA MONITOR'' mode with CONSULT.
3) Wait at least 5 seconds.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------OR-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
1) Turn ignition switch ``ON'' and wait at least 5 seconds.
2) Turn ignition switch ``OFF'', wait at least 5 seconds and
then turn ``ON''.
3) Perform ``Diagnostic Test Mode II (Self-diagnostic
results)'' with ECM.
SEF594K
SEF012P
SEF741V
TROUBLE DIAGNOSIS FOR ``COOLANT TEMP SEN'' (DTC 13)
EC-79

TEC425
TROUBLE DIAGNOSIS FOR ``COOLANT TEMP SEN'' (DTC 13)
Engine Coolant Temperature (ECT) Sensor
(Cont'd)
EC-80

DIAGNOSTIC PROCEDURE
INSPECTION START
CHECK POWER SUPPLY.
1. Turn ignition switch ``OFF''.
2. Disconnect engine coolant temperature
sensor harness connector.
3. Turn ignition switch ``ON''.
4. Check voltage between terminal
V2and ground with CONSULT or tester.
Voltage:
Approximately 5V
OK
cNG
Check the following.
+Harness connectors
E202,E69+Harness connectorsE127,M21+Harness connectorsM51,F6+Harness for open or
short between ECM and
engine coolant tempera-
ture sensor
If NG, repair harness or
connectors.
CHECK GROUND CIRCUIT.
1. Turn ignition switch ``OFF''.
2. Check harness continuity between ter-
minal
V1and engine ground.
Continuity should exist.
If OK, check harness for short to
ground and short to power.
OK
cNG
Check the following.
+Harness connectors
E202,E69+Harness connectorsE127,M21+Harness connectorsM50,F5+Harness connectorsF6,M51+Harness connectorsM88,E106+Harness for open or
short between ECM and
engine coolant tempera-
ture sensor
+Harness for open or
short between TCM and
engine coolant tempera-
ture sensor
If NG, repair open circuit or
short to ground or short to
power in harness or con-
nectors.
CHECK COMPONENT
(Engine coolant temperature sensor).
Refer to ``COMPONENT INSPECTION''
on next page.
OK
cNG
Replace engine coolant
temperature sensor.
Disconnect and reconnect harness con-
nectors in the circuit. Then retest.
Trouble is not ®xed.
Check ECM pin terminals for damage and
check the connection of ECM harness
connector. Reconnect ECM harness con-
nector and retest.
INSPECTION END
SEF678V
SEF541P
SEF542P
.
.
.
.
.
.
TROUBLE DIAGNOSIS FOR ``COOLANT TEMP SEN'' (DTC 13)
Engine Coolant Temperature (ECT) Sensor
(Cont'd)
EC-81