INFINITI QX4 2001 Factory Service Manual

Wiring DiagramNBEC0067
MEC944C
DTC P0110 INTAKE AIR TEMPERATURE SENSOR
Wiring Diagram
EC-166

Diagnostic ProcedureNBEC0068
1 CHECK INTAKE AIR TEMPERATURE SENSOR POWER SUPPLY CIRCUIT
1. Turn ignition switch ªOFFº.
2. Disconnect intake air temperature sensor harness connector.
SEF962Y
3. Turn ignition switch ªONº.
4. Check voltage between terminal 1 and ground.
SEF301X
OK or NG
OK©GO TO 3.
NG©GO TO 2.
2 DETECT MALFUNCTIONING PART
Check the following.
IHarness connectors E1, M1
IHarness connectors M33, F22
IHarness for open or short between ECM and intake air temperature sensor
©Repair harness or connectors.
3 CHECK INTAKE AIR TEMPERATURE SENSOR GROUND CIRCUIT FOR OPEN AND SHORT
1. Turn ignition switch ªOFFº.
2. Check harness continuity between sensor terminal 2 and engine ground.
Refer to Wiring Diagram.
Continuity should exist.
3. Also check harness for short to power.
OK or NG
OK©GO TO 5.
NG©GO TO 4.
GI
MA
EM
LC
FE
AT
TF
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
DTC P0110 INTAKE AIR TEMPERATURE SENSOR
Diagnostic Procedure
EC-167

4 DETECT MALFUNCTIONING PART
Check the following.
IHarness connectors E1, M1
IHarness connectors M33, F22
IHarness for open between ECM and intake air temperature sensor
IHarness for open between TCM (Transmission Control Module) and intake air temperature sensor
©Repair open circuit or short to power in harness or connectors.
5 CHECK INTAKE AIR TEMPERATURE SENSOR
Check resistance between intake air temperature sensor terminals 1 and 2 as shown in the figure.
SEF302X
OK or NG
OK©GO TO 6.
NG©Replace intake air temperature sensor.
6 CHECK INTERMITTENT INCIDENT
Refer to ªTROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENTº, EC-140.
©INSPECTION END
DTC P0110 INTAKE AIR TEMPERATURE SENSOR
Diagnostic Procedure (Cont'd)
EC-168

SEF594K
Component DescriptionNBEC0069The 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* V Resistance 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.
On Board Diagnosis LogicNBEC0070Malfunction is detected when an excessively high or low voltage
from the sensor is sent to ECM.
FAIL-SAFE MODENBEC0070S02When this malfunction is detected, the ECM enters fail-safe mode
and the MIL lights up.
Detected items Engine operating condition in fail-safe mode
Engine coolant tem-
perature 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)
GI
MA
EM
LC
FE
AT
TF
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
DTC P0115 ENGINE COOLANT TEMPERATURE SENSOR (ECTS) (CIRCUIT)
Component Description
EC-169

Possible CauseNBEC0429IHarness or connectors
(The sensor circuit is open or shorted.)
IEngine coolant temperature sensor
SEF058Y
DTC Confirmation ProcedureNBEC0071NOTE:
If ªDTC Confirmation Procedureº has been previously conducted,
always turn ignition switch ªOFFº and wait at least 10 seconds
before conducting the next test.
WITH CONSULT-IINBEC0071S011) Turn ignition switch ªONº.
2) Select ªDATA MONITORº mode with CONSULT-II.
3) Wait at least 5 seconds.
4) If 1st trip DTC is detected, go to ªDiagnostic Procedureº,
EC-172.
WITH GSTNBEC0071S02Follow the procedure ªWITH CONSULT-IIº above.
DTC P0115 ENGINE COOLANT TEMPERATURE SENSOR (ECTS) (CIRCUIT)
Possible Cause
EC-170

Wiring DiagramNBEC0072
MEC945C
GI
MA
EM
LC
FE
AT
TF
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
DTC P0115 ENGINE COOLANT TEMPERATURE SENSOR (ECTS) (CIRCUIT)
Wiring Diagram
EC-171

Diagnostic ProcedureNBEC0073
1 CHECK ECTS POWER SUPPLY CIRCUIT
1. Turn ignition switch ªOFFº.
2. Disconnect engine coolant temperature sensor (ECTS) harness connector F112, F28.
SEF370Z
3. Turn ignition switch ªONº.
4. Check voltage between ECTS harness connector F28 terminal 3 and ground with CONSULT-II or tester.
SEF371Z
OK or NG
OK©GO TO 3.
NG©GO TO 2.
2 DETECT MALFUNCTIONING PART
Check the following.
IHarness connectors F112, F28
IHarness for open or short between ECM and engine coolant temperature sensor
©Repair harness or connectors.
3 CHECK ECTS GROUND CIRCUIT FOR OPEN AND CIRCUIT
1. Turn ignition switch ªOFFº.
2. Check harness continuity between ECTS terminal 2 and engine ground.
Refer to Wiring Diagram.
Continuity should exist.
3. Also check harness for short to power.
OK or NG
OK©GO TO 5.
NG©GO TO 4.
DTC P0115 ENGINE COOLANT TEMPERATURE SENSOR (ECTS) (CIRCUIT)
Diagnostic Procedure
EC-172

4 DETECT MALFUNCTIONING PART
Check the following.
IHarness connectors F112, F28
IHarness for open between ECM and engine coolant temperature sensor
IHarness for open between TCM (Transmission Control Module) and engine coolant temperature sensor
©Repair open circuit or short to power in harness or connectors.
5 CHECK ENGINE COOLANT TEMPERATURE SENSOR
Check resistance between engine coolant temperature sensor terminals 1 and 2 as shown in the figure.
SEF304X
OK or NG
OK©GO TO 6.
NG©Replace engine coolant temperature sensor.
6 CHECK INTERMITTENT INCIDENT
Refer to ªTROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENTº, EC-140.
©INSPECTION END
GI
MA
EM
LC
FE
AT
TF
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
DTC P0115 ENGINE COOLANT TEMPERATURE SENSOR (ECTS) (CIRCUIT)
Diagnostic Procedure (Cont'd)
EC-173

DescriptionNBEC0074NOTE:
If DTC P0120 is displayed with DTC P0510, first perform the trouble diagnosis for DTC P0510. Refer to
EC-431.
COMPONENT DESCRIPTIONNBEC0074S01The throttle position sensor responds to the accelerator pedal movement. This sensor is a kind of potentiom-
eter which transforms the throttle position into output voltage, and emits the voltage signal to the ECM. In
addition, the sensor detects the opening and closing speed of the throttle valve and feeds the voltage signal
to the ECM.
Idle position of the throttle valve is determined by the ECM receiving the signal from the throttle position sen-
sor. This sensor controls engine operation such as fuel cut. On the other hand, the ªWide open and closed
throttle position switchº, which is built into the throttle position sensor unit, is not used for engine control.
AEC929
CONSULT-II Reference Value in Data Monitor
Mode
NBEC0075Specification data are reference values.
MONITOR ITEM CONDITION SPECIFICATION
THRTL POS SENIEngine: After warming up, idle
the engineThrottle valve: fully closed 0.15 - 0.85V
IEngine: After warming up
IIgnition switch: ON
(Engine stopped)Throttle valve: fully opened 3.5 - 4.7V
ABSOL TH´P/SIEngine: After warming up, idle
the engineThrottle valve: fully closed 0.0%
IEngine: After warming up
IIgnition switch: ON
(Engine stopped)Throttle valve: fully opened Approx. 80%
DTC P0120 THROTTLE POSITION SENSOR
Description
EC-174

ECM Terminals and Reference Value=NBEC0651Specification 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.
TERMI-
NAL
NO.WIRE
COLORITEM CONDITION DATA (DC Voltage)
91 R Throttle position sensor[Engine is running]
IWarm-up condition
IAccelerator pedal fully released0.15 - 0.85V
[Ignition switch ªONº]
IAccelerator pedal fully depressed3.5 - 4.7V
111 P/B Sensors' power supply[Ignition switch ªONº]Approximately 5V
58 B/P Sensors' ground[Engine is running]
IWarm-up condition
IIdle speedApproximately 0V
On Board Diagnosis LogicNBEC0077Malfunction is detected when
(Malfunction A)an excessively low or high voltage from the sen-
sor is sent to ECM,
(Malfunction B)a high voltage from the sensor is sent to ECM
under light load driving conditions,
(Malfunction C)a low voltage from the sensor is sent to ECM
under heavy load driving conditions.
FAIL-SAFE MODENBEC0077S02When the malfunction A is detected, the ECM enters fail-safe mode
and the MIL 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
Possible CauseNBEC0430MALFUNCTION ANBEC0430S01IHarness or connectors
(The throttle position sensor circuit is open or shorted.)
IThrottle position sensor
MALFUNCTION BNBEC0430S02IHarness or connectors
(The throttle position sensor circuit is open or shorted.)
IThrottle position sensor
IFuel injector
GI
MA
EM
LC
FE
AT
TF
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
DTC P0120 THROTTLE POSITION SENSOR
ECM Terminals and Reference Value
EC-175