Nissan Frontier D22. Manual - part 411

DTC P0121 TP SENSOR

EC-747

[VG33E]

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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 the ECM terminals, such as the ground.

Diagnostic Procedure

UBS00DGZ

1. 

INSPECTION START

Which malfunction (A or B) is duplicated?

A or B

A

>> GO  TO  4.

B

>> GO  TO  2.

2. 

ADJUST THROTTLE POSITION SENSOR

Check the following items. Refer to 

EC-646, "Basic Inspection"

 .

>> GO TO 3. 

3. 

CHECK INTAKE SYSTEM.

1.

Turn ignition switch OFF.

2.

Check the following for connection.

–

Air duct

–

Vacuum hoses

–

Intake air passage between air duct to intake manifold collector

OK or NG

OK

>> GO TO 4.

NG

>> Reconnect the parts.

TER-

MINAL 

NO.

WIRE 

COLOR

ITEM

CONDITION

DATA (DC Voltage)

23

L

Throttle position sensor

[Engine is running]

●

Warm-up condition

●

More than -40.0 kpa (-300 mmHg, -11.81 inHg) 
of vacuum is applied to the throttle opener with 
a hand vacuum pump

●

Accelerator pedal is fully released

0.15 - 0.85V

 [Ignition switch: ON]

●

Engine stopped

●

Accelerator pedal is fully depressed

3.5 - 4.7V

42

B/W

Sensor power supply

[Ignition switch: ON]

Approximately 5V

43

BR

Sensor ground

[Engine is running]

●

Warm-up condition

●

Idle speed

Approximately 0V

Items

Specifications

Ignitions timing

10 

± 5° BTDC

Base idle speed

700 

± 50 rpm (in P or N position)

Closed throttle position switch idle 
position adjustment

Feeler gauge thickness and switch 
condition
0.3 mm (0.012 in): ON
0.4 mm (0.016 in): OFF

Target idle speed

750 

± 50 rpm (in P or N position)

EC-748

[VG33E]

DTC P0121 TP SENSOR

4. 

RETIGHTEN GROUND SCREWS

1.

Turn ignition switch OFF.

2.

Loosen and retighten engine ground screws.

>> GO TO 5.

5. 

CHECK THROTTLE POSITION SENSOR POWER SUPPLY CIRCUIT

1.

Disconnect throttle position sensor harness connector.

2.

Turn ignition switch ON.

3.

Check voltage between sensor terminal 3 and ground with CON-
SULT-II or tester.

OK or NG

OK

>> GO TO 6.

NG

>> Repair open circuit or short to ground or short to power

in harness or connectors.

6. 

CHECK THROTTLE POSITION SENSOR GROUND CIRCUIT FOR OPEN AND SHORT

1.

Turn ignition switch OFF.

2.

Check harness continuity between throttle position sensor terminal 1 and engine ground.
Refer to Wiring Diagram.

3.

Also check harness for short to power.

OK or NG

OK

>> GO TO 8.

NG

>> GO TO 7.

7. 

DETECT MALFUNCTIONING PART

Check the harness for open or short between ECM and throttle position sensor.

>> Repair open circuit or short to power in harness or connectors.

BBIA0418E

AEC638A

Voltage: Approximately 5V

SEF630W

Continuity should exist.

DTC P0121 TP SENSOR

EC-749

[VG33E]

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8. 

CHECK THROTTLE POSITION SENSOR INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT

1.

Disconnect ECM harness connector.

2.

Check harness continuity between ECM terminal 23 and throttle position sensor terminal 2.
Refer to Wiring Diagram.

3.

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 THROTTLE POSITION SENSOR

Refer to 

EC-751, "Component Inspection"

 .

OK or NG

OK

>> GO TO 11.

NG

>> GO TO 10.

10. 

ADJUST CLOSED THROTTLE POSITION SWITCH

Adjust closed throttle position switch. Refer to 

EC-646, "Basic Inspection"

 .

OK or NG

OK

>> GO TO 11.

NG

>> Replace throttle position sensor. To adjust it, perform 

EC-646, "Basic Inspection"

 . 

11. 

CHECK MASS AIR FLOW SENSOR

Refer to 

EC-726, "Component Inspection"

 .

OK or NG

OK

>> GO TO 12.

NG

>> Replace mass air flow sensor.

Continuity should exist.

Items

Specifications

Ignitions timing

10 

± 5° BTDC

Base idle speed

700 

± 50 rpm (in P or N position)

Closed throttle position switch idle 
position adjustment

Feeler gauge thickness and switch 
condition
0.3 mm (0.012 in): ON
0.4 mm (0.016 in): OFF

Target idle speed

750 

± 50 rpm (in P or N position)

EC-750

[VG33E]

DTC P0121 TP SENSOR

12. 

CHECK CAMSHAFT POSITION SENSOR

1.

Install any parts removed.

2.

Start engine.

3.

Check voltage between ECM terminals 44, 48 and ground, ECM
terminal 49 and ground with DC range.
<Terminal 44 or 48 and engine ground>

<Terminal 49 and engine ground>

OK or NG

OK

>> GO TO 13.

NG

>> Replace distributor assembly with camshaft position sensor.

13. 

CHECK FUEL INJECTOR

1.

Disconnect injector harness connector.

2.

Check resistance between terminals as shown in the figure.

OK or NG

OK

>> GO TO 14.

NG

>> Replace fuel injector.

14. 

CHECK INTERMITTENT INCIDENT

Refer to 

EC-696, "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT"

 .

>> INSPECTION END.

Condition

Idle

2,000 rpm

Voltage

0.3 - 0.5V

0.3 - 0.5V

Pulse sig-

nal

Condition

Idle

2,000 rpm

Voltage

Approximately 2.5V

Approximately 2.5V

Pulse sig-

nal

PBIB1424E

SEF997U

SEF998U

SEF999U

SEF001V

Resistance: 10 - 14

Ω [at 25°C (77°F)]

SEF625V