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Home >> Nissan-Datsun >> 2004 >> Frontier Base, Standard >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 4 (Engine Control System - VG33ER) >> DTC P0121: TP Sensor >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different variant/trim than selected.
  1. INSPECTION START 

    Which malfunction (A or B) is duplicated?

    A or B 

    1. A : GO TO  4.
    2. B : GO TO 2.
  2. ADJUST THROTTLE POSITION SENSOR 

    Check the following items. Refer to "BASIC INSPECTION "

    Fig 1: Item Specification Chart
    G00771847Courtesy of NISSAN MOTOR CO., U.S.A.
    1. : 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 

    1. OK : GO TO 4.
    2. NG : Reconnect the parts.
  4. RETIGHTEN GROUND SCREWS 
    1. Turn ignition switch OFF.
    2. Loosen and retighten engine ground screws.
      1. : GO TO 5.
      Fig 2: Retightening Engine Ground Screws
      G00771848Courtesy of NISSAN MOTOR CO., U.S.A.
  5. CHECK THROTTLE POSITION SENSOR POWER SUPPLY CIRCUIT 
    1. Disconnect throttle position sensor harness connector.
    2. Turn ignition switch ON.
      Fig 3: Disconnecting Throttle Position Sensor Harness Connector
      G00771849Courtesy of NISSAN MOTOR CO., U.S.A.
    3. Check voltage between sensor terminal 3 and ground with CONSULT-II or tester.
      1. Voltage: Approximately 5V 

    OK or NG 

    1. OK : GO TO 6.
    2. NG : Repair open circuit or short to ground or short to power in harness or connectors.
    Fig 4: Checking Voltage Between Sensor Terminal 3 And Ground
    G00771850Courtesy of NISSAN MOTOR CO., U.S.A.
  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 .

      1. Continuity should exist. 
    3. Also check harness for short to power.

    OK or NG 

    1. OK : GO TO  8.
    2. NG : GO TO 7.
  7. DETECT MALFUNCTIONING PART 

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

    1. : Repair open circuit or short to power in harness or connectors.
  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 .
      1. Continuity should exist. 
    3. Also check harness for short to ground and short to power.

    OK or NG 

    1. OK : GO TO 9.
    2. NG : Repair open circuit or short to ground or short to power in harness or connectors.
  9. CHECK THROTTLE POSITION SENSOR 

    Refer to "COMPONENT INSPECTION ".

    OK or NG 

    1. OK : GO TO  11.
    2. NG : GO TO  10.
  10. ADJUST CLOSED THROTTLE POSITION SWITCH 

    Adjust closed throttle position switch. Refer to "BASIC INSPECTION ".

    Fig 5: Item Specification Chart
    G00771851Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    1. OK : GO TO 11.
    2. NG : Replace throttle position sensor. To adjust it, perform "BASIC INSPECTION ".
  11. CHECK MASS AIR FLOW SENSOR 

    Refer to "COMPONENT INSPECTION ".

    OK or NG 

    1. OK : GO TO 12.
    2. NG : Replace mass air flow 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.
      1. < Terminal 44 or 48 and engine ground > 
      Fig 6: ECM Ground Terminal Chart
      G00771852Courtesy of NISSAN MOTOR CO., U.S.A.
      Fig 7: ECM Ground Terminal Chart
      G00771853Courtesy of NISSAN MOTOR CO., U.S.A.
      1. < Terminal 49 and engine ground > 
      Fig 8: Checking Voltage Between ECM Terminals 44, 48 And Ground, ECM Terminal 49 And Ground
      G00771854Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    1. OK : GO TO 13.
    2. 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.
      1. Resistance: 10 -14Ω [at 25°C(77°F)] 

    OK or NG 

    1. OK : GO TO 14.
    2. NG : Replace fuel injector.
    Fig 9: Checking Resistance Between Terminals
    G00771855Courtesy of NISSAN MOTOR CO., U.S.A.
  14. CHECK INTERMITTENT INCIDENT 

    Refer to "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT ".

    1. : INSPECTION END.