Ins INFINITI QX56 2004 Factory Service Manual

EC-556Revision: August 2007
DTC P2122, P2123 APP SENSOR
2004 QX56
DTC P2122, P2123 APP SENSORPFP:18002
Component DescriptionUBS00HC4
The accelerator pedal position sensor is installed on the upper end
of the accelerator pedal assembly. The sensor detects the accelera-
tor position and sends a signal to the ECM.
Accelerator pedal position sensor has two sensors. These sensors
are a kind of potentiometers which transform the accelerator pedal
position into output voltage, and emit the voltage signal to the ECM.
In addition, these sensors detect the opening and closing speed of
the accelerator pedal and feed the voltage signals to the ECM. The
ECM judges the current opening angle of the accelerator pedal from
these signals and controls the throttle control motor based on these
signals.
Idle position of the accelerator pedal is determined by the ECM
receiving the signal from the accelerator pedal position sensor. The ECM uses this signal for the engine oper-
ation such as fuel cut.
CONSULT-II Reference Value in Data Monitor ModeUBS00HC5
Specification data are reference values.
*: Accelerator pedal position sensor 2 signal is converted by ECM internally. Thus, it differ from ECM terminal voltage.
On Board Diagnosis LogicUBS00HC6
These self-diagnoses have the one trip detection logic.
NOTE:
If DTC P2122 or P2123 is displayed with DTC P1229, first perform the trouble diagnosis for DTC P1229.
Refer to EC-424, "
DTC P1229 SENSOR POWER SUPPLY" .
FAIL -S AFE M OD E
When the malfunction is detected, ECM enters fail-safe mode and the MIL lights up.
PBIB1741E
MONITOR ITEM CONDITION SPECIFICATION
ACCEL SEN1

Ignition switch: ON
(Engine stopped)Accelerator pedal: Fully released 0.5 - 1.0V
Accelerator pedal: Fully depressed 4.2 - 4.8V
ACCEL SEN2*

Ignition switch: ON
(Engine stopped)Accelerator pedal: Fully released 0.5 - 1.0V
Accelerator pedal: Fully depressed 4.2 - 4.8V
CLSD THL POS

Ignition switch: ON
(Engine stopped)Accelerator pedal: Fully released ON
Accelerator pedal: Slightly depressed OFF
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P2122
2122Accelerator pedal position
sensor 1 circuit low inputAn excessively low voltage from the APP sen-
sor 1 is sent to ECM.

Harness or connectors
(The APP sensor 1 circuit is open or
shorted.)

Accelerator pedal position sensor
(Accelerator pedal position sensor 1) P2123
2123Accelerator pedal position
sensor 1 circuit high inputAn excessively high voltage from the APP sen-
sor 1 is sent to ECM.
Engine operating condition in fail-safe mode
The ECM controls the electric throttle control actuator in regulating the throttle opening in order for the idle position to be within +10
degrees.
The ECM regulates the opening speed of the throttle valve to be slower than the normal condition.
So, the acceleration will be poor.

DTC P2122, P2123 APP SENSOR
EC-559
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EC
Revision: August 20072004 QX56
Specification 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.
Diagnostic ProcedureUBS00HC9
1. CHECK GROUND CONNECTIONS
1. Turn ignition switch OFF.
2. Loosen and retighten three ground screws on the body.
Refer to EC-133, "
Ground Inspection" .
OK or NG
OK >> GO TO 2.
NG >> Repair or replace ground connections.
TER-
MINAL
NO.WIRE
COLORITEM CONDITION DATA (DC Voltage)
82 B/RSensor ground
(APP sensor 1)[Engine is running]

Warm-up condition

Idle speedApproximately 0V
83 G/WSensor ground
(APP sensor 2)[Engine is running]

Warm-up condition

Idle speedApproximately 0V
90 LSensor power supply
(APP sensor 1)[Ignition switch: ON]Approximately 5V
91 W/RSensor power supply
(APP sensor 2)[Ignition switch: ON]Approximately 5V
98 G/RAccelerator pedal position
sensor 2[Ignition switch: ON]

Engine stopped

Accelerator pedal: Fully released0.25 - 0.50V
[Ignition switch: ON]

Engine stopped

Accelerator pedal: Fully depressed2.0 - 2.5V
106 BR/WAccelerator pedal position
sensor 1[Ignition switch: ON]

Engine stopped

Accelerator pedal: Fully released0.5 - 1.0V
[Ignition switch: ON]

Engine stopped

Accelerator pedal: Fully depressed4.2 - 4.8V
BBIA0354E

EC-560Revision: August 2007
DTC P2122, P2123 APP SENSOR
2004 QX56
2. CHECK APP SENSOR 1 POWER SUPPLY CIRCUIT
1. Disconnect accelerator pedal position (APP) sensor harness
connector.
2. Turn ignition switch ON.
3. Check voltage between APP sensor terminal 7 and ground with
CONSULT-II or tester.
OK or NG
OK >> GO TO 3.
NG >> Repair open circuit or short to ground or short to power
in harness or connectors.
3. CHECK APP SENSOR 1 GROUND CIRCUIT FOR OPEN AND SHORT
1. Turn ignition switch OFF.
2. Disconnect ECM harness connector.
3. Check harness continuity between ECM terminal 82 and APP sensor terminal 1.
Refer to Wiring Diagram.
4. Also check harness for short to ground and short to power.
OK or NG
OK >> GO TO 4.
NG >> Repair open circuit or short to ground or short to power in harness or connectors.
4. CHECK APP SENSOR INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
1. Check harness continuity between ECM terminal 106 and APP sensor terminal 2.
Refer to Wiring Diagram.
2. Also check harness for short to ground and short to power.
OK or NG
OK >> GO TO 5.
NG >> Repair open circuit or short to ground or short to power in harness or connectors.
5. CHECK APP SENSOR
Refer to EC-561, "
Component Inspection" .
OK or NG
OK >> GO TO 7.
NG >> GO TO 6.
BBIA0361E
Voltage: Approximately 5V
PBIB2070E
Continuity should exist.
Continuity should exist.

DTC P2122, P2123 APP SENSOR
EC-561
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EC
Revision: August 20072004 QX56
6. REPLACE ACCELERATOR PEDAL ASSEMBLY
1. Replace the accelerator pedal assembly.
2. Perform EC-44, "
Accelerator Pedal Released Position Learning" .
3. Perform EC-44, "
Throttle Valve Closed Position Learning" .
4. Perform EC-44, "
Idle Air Volume Learning" .
>>INSPECTION END
7. CHECK INTERMITTENT INCIDENT
Refer to EC-127, "
TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT" .
>>INSPECTION END
Component InspectionUBS00HCA
ACCELERATOR PEDAL POSITION SENSOR
1. Reconnect all harness connectors disconnected.
2. Turn ignition switch ON.
3. Check voltage between ECM terminals 106 (APP sensor 1 sig-
nal), 98 (APP sensor 2 signal) and ground under the following
conditions.
4. If NG, replace accelerator pedal assembly and go to next step.
5. Perform EC-44, "
Accelerator Pedal Released Position Learning" .
6. Perform EC-44, "
Throttle Valve Closed Position Learning" .
7. Perform EC-44, "
Idle Air Volume Learning" .
Removal and InstallationUBS00HCB
ACCELERATOR PEDAL
Refer to ACC-2, "ACCELERATOR CONTROL SYSTEM" .
Terminal Accelerator pedal Voltage
106
(Accelerator pedal position
sensor 1)Fully released 0.5 - 1.0V
Fully depressed 4.2 - 4.8V
98
(Accelerator pedal position
sensor 2)Fully released 0.25 - 0.5V
Fully depressed 2.0 - 2.5V
MBIB0023E

EC-562Revision: August 2007
DTC P2127, P2128 APP SENSOR
2004 QX56
DTC P2127, P2128 APP SENSORPFP:18002
Component DescriptionUBS00HCC
The accelerator pedal position sensor is installed on the upper end
of the accelerator pedal assembly. The sensor detects the accelera-
tor position and sends a signal to the ECM.
Accelerator pedal position sensor has two sensors. These sensors
are a kind of potentiometers which transform the accelerator pedal
position into output voltage, and emit the voltage signal to the ECM.
In addition, these sensors detect the opening and closing speed of
the accelerator pedal and feed the voltage signals to the ECM. The
ECM judges the current opening angle of the accelerator pedal from
these signals and controls the throttle control motor based on these
signals.
Idle position of the accelerator pedal is determined by the ECM
receiving the signal from the accelerator pedal position sensor. The ECM uses this signal for the engine oper-
ation such as fuel cut.
CONSULT-II Reference Value in Data Monitor ModeUBS00HCD
Specification data are reference values.
*: Accelerator pedal position sensor 2 signal is converted by ECM internally. Thus, it differ from ECM terminal voltage.
On Board Diagnosis LogicUBS00HCE
These self-diagnoses have the one trip detection logic.
FAIL -S AFE M OD E
When the malfunction is detected, ECM enters fail-safe mode and the MIL lights up.
PBIB1741E
MONITOR ITEM CONDITION SPECIFICATION
ACCEL SEN1

Ignition switch: ON
(Engine stopped)Accelerator pedal: Fully released 0.5 - 1.0V
Accelerator pedal: Fully depressed 4.2 - 4.8V
ACCEL SEN2*

Ignition switch: ON
(Engine stopped)Accelerator pedal: Fully released 0.5 - 1.0V
Accelerator pedal: Fully depressed 4.2 - 4.8V
CLSD THL POS

Ignition switch: ON
(Engine stopped)Accelerator pedal: Fully released ON
Accelerator pedal: Slightly depressed OFF
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P2127
2127Accelerator pedal position
sensor 2 circuit low inputAn excessively low voltage from the APP
sensor 2 is sent to ECM.

Harness or connectors
(APP sensor 2 circuit is open or shorted.)
(TP sensor circuit is shorted.)

Accelerator pedal position sensor
(Accelerator pedal position sensor 2)

Electric throttle control actuator
(TP sensor) P2128
2128Accelerator pedal position
sensor 2 circuit high inputAn excessively high voltage from the APP
sensor 2 is sent to ECM.
Engine operating condition in fail-safe mode
The ECM controls the electric throttle control actuator in regulating the throttle opening in order for the idle position to be within +10
degrees.
The ECM regulates the opening speed of the throttle valve to be slower than the normal condition.
So, the acceleration will be poor.

DTC P2127, P2128 APP SENSOR
EC-565
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EC
Revision: August 20072004 QX56
Specification 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.
Diagnostic ProcedureUBS00HCH
1. CHECK GROUND CONNECTIONS
1. Turn ignition switch OFF.
2. Loosen and retighten three ground screws on the body.
Refer to EC-133, "
Ground Inspection" .
OK or NG
OK >> GO TO 2.
NG >> Repair or replace ground connections.
TER-
MINAL
NO.WIRE
COLORITEM CONDITION DATA (DC Voltage)
47 YSensor power supply
(TP sensor)[Ignition switch: ON]Approximately 5V
82 B/RSensor ground
(APP sensor 1)[Engine is running]

Warm-up condition

Idle speedApproximately 0V
83 G/WSensor ground
(APP sensor 2)[Engine is running]

Warm-up condition

Idle speed Approximately 0V
90 LSensor power supply
(APP sensor 1)[Ignition switch: ON]Approximately 5V
91 W/RSensor power supply
(APP sensor 2)[Ignition switch: ON]Approximately 5V
98 G/RAccelerator pedal position
sensor 2[Ignition switch: ON]

Engine stopped

Accelerator pedal: Fully released0.25 - 0.50V
[Ignition switch: ON]

Engine stopped

Accelerator pedal: Fully depressed2.0 - 2.5V
106 BR/WAccelerator pedal position
sensor 1[Ignition switch: ON]

Engine stopped

Accelerator pedal: Fully released0.5 - 1.0V
[Ignition switch: ON]

Engine stopped

Accelerator pedal: Fully depressed4.2 - 4.8V
BBIA0354E

EC-566Revision: August 2007
DTC P2127, P2128 APP SENSOR
2004 QX56
2. CHECK APP SENSOR 2 POWER SUPPLY CIRCUIT-I
1. Disconnect accelerator pedal position (APP) sensor harness
connector.
2. Turn ignition switch ON.
3. Check voltage between APP sensor terminal 6 and ground with
CONSULT-II or tester.
OK or NG
OK >> GO TO 7.
NG >> GO TO 3.
3. CHECK APP SENSOR 2 POWER SUPPLY CIRCUIT-II
1. Turn ignition switch OFF.
2. Disconnect ECM harness connector.
3. Check harness continuity between APP sensor terminal 6 and ECM terminal 91.
Refer to Wiring Diagram.
OK or NG
OK >> GO TO 4.
NG >> Repair or replace open circuit.
4. CHECK APP SENSOR 2 POWER SUPPLY CIRCUIT-II
Check the following.

Harness for short to power and short to ground, between the following terminals
OK or NG
OK >> GO TO 5.
NG >> Repair short to ground or short to power in harness or connectors.
5. CHECK THROTTLE POSITION SENSOR
Refer to EC-575, "
Component Inspection" .
OK or NG
OK >> GO TO 11.
NG >> GO TO 6.
BBIA0361E
Voltage: Approximately 5V
PBIB2069E
Continuity should exist.
ECM terminal Sensor terminal Reference Wiring Diagram
47 Electric throttle control actuator terminal 2EC-571
91 APP sensor terminal 6EC-564

DTC P2127, P2128 APP SENSOR
EC-567
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EC
Revision: August 20072004 QX56
6. REPLACE ELECTRIC THROTTLE CONTROL ACTUATOR
1. Replace the electric throttle control actuator.
2. Perform EC-44, "
Throttle Valve Closed Position Learning" .
3. Perform EC-44, "
Idle Air Volume Learning" .
>>INSPECTION END
7. CHECK APP SENSOR 2 GROUND CIRCUIT FOR OPEN AND SHORT
1. Turn ignition switch OFF.
2. Disconnect ECM harness connector.
3. Check harness continuity between ECM terminal 83 and APP sensor terminal 3.
Refer to Wiring Diagram.
4. 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 APP SENSOR 2 INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
1. Check harness continuity between ECM terminal 98 and APP sensor terminal 5.
Refer to Wiring Diagram.
2. Also check harness for short to ground and short to power.
OK or NG
OK >> GO TO 9.
NG >> Repair open circuit or short to ground or short to power in harness or connectors.
9. CHECK APP SENSOR
Refer to EC-561, "
Component Inspection" .
OK or NG
OK >> GO TO 11.
NG >> GO TO 10.
10. REPLACE ACCELERATOR PEDAL ASSEMBLY
1. Replace the accelerator pedal assembly.
2. Perform EC-44, "
Accelerator Pedal Released Position Learning" .
3. Perform EC-44, "
Throttle Valve Closed Position Learning" .
4. Perform EC-44, "
Idle Air Volume Learning" .
>>INSPECTION END
11 . CHECK INTERMITTENT INCIDENT
Refer to EC-127, "
TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT" .
>>INSPECTION END Continuity should exist.
Continuity should exist.

EC-568Revision: August 2007
DTC P2127, P2128 APP SENSOR
2004 QX56
Component InspectionUBS00HCI
ACCELERATOR PEDAL POSITION SENSOR
1. Reconnect all harness connectors disconnected.
2. Turn ignition switch ON.
3. Check voltage between ECM terminals 106 (APP sensor 1 sig-
nal), 98 (APP sensor 2 signal) and ground under the following
conditions.
4. If NG, replace accelerator pedal assembly and go to next step.
5. Perform EC-44, "
Accelerator Pedal Released Position Learning" .
6. Perform EC-44, "
Throttle Valve Closed Position Learning" .
7. Perform EC-44, "
Idle Air Volume Learning" .
Removal and InstallationUBS00HCJ
ACCELERATOR PEDAL
Refer to ACC-2, "ACCELERATOR CONTROL SYSTEM" .
Terminal Accelerator pedal Voltage
106
(Accelerator pedal position
sensor 1)Fully released 0.5 - 1.0V
Fully depressed 4.2 - 4.8V
98
(Accelerator pedal position
sensor 2)Fully released 0.25 - 0.5V
Fully depressed 2.0 - 2.5V
MBIB0023E

EC-572Revision: August 2007
DTC P2135 TP SENSOR
2004 QX56
Specification 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.
Diagnostic ProcedureUBS00HCP
1. CHECK GROUND CONNECTIONS
1. Turn ignition switch OFF.
2. Loosen and retighten three ground screws on the body.
Refer to EC-133, "
Ground Inspection" .
OK or NG
OK >> GO TO 2.
NG >> Repair or replace ground connections.
TER-
MINAL
NO. WIRE
COLORITEM CONDITION DATA (DC Voltage)
47 YSensor power supply
(Throttle position sensor)[Ignition switch: ON]Approximately 5V
50 B Throttle position sensor 1[Ignition switch: ON]

Engine stopped

Shift lever: D

Accelerator pedal: Fully releasedMore than 0.36V
[Ignition switch: ON]

Engine stopped

Shift lever: D

Accelerator pedal: Fully depressedLess than 4.75V
66 RSensor ground
(Throttle position sensor)[Engine is running]

Warm-up condition

Idle speedApproximately 0V
69 W Throttle position sensor 2[Ignition switch: ON]

Engine stopped

Shift lever: D

Accelerator pedal: Fully releasedLess than 4.75V
[Ignition switch: ON]

Engine stopped

Shift lever: D

Accelerator pedal: Fully depressedMore than 0.36V
91 W/RSensor power supply
(APP sensor 2)[Ignition switch: ON]Approximately 5V
BBIA0354E