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Home >> Nissan-Datsun >> 2003 >> Sentra Limited >> Repair and Diagnosis >> External Pages >> Different car >> Section 39 (Engine Controls - Self-Diagnostics - 1.8L - XE, GXE) >> Diagnostic Tests >> DTC P0121, DTC P0122 Or DTC P0123: TP Sensor >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different car, the 2002 Nissan Sentra. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: For circuit wiring diagram, see Fig 1 . For connector identification and locations, see CONNECTOR IDENTIFICATION  .
  1. If malfunction "A" or "B" is detected, go to step  4 . If malfunction "C" is detected, go to next step.

  2. Adjust TP Sensor

    Adjust TP sensor by performing BASIC INSPECTION. See ON-VEHICLE ADJUSTMENTS article. Go to next step.

  3. Check Intake System

    Check the following connections:
    • Air duct.
    • Vacuum hoses.
    • Intake air passage between air duct and intake manifold collector.

    If problem is found, repair as necessary. Perform appropriate DTC CONFIRMATION TEST to verify repair. If problem is not found, go to next step.

  4. Retighten Ground Screws

    Turn ignition off. Loosen and retighten engine ground screws. See Figure . Go to next step.

  5. Check Power Supply

    Disconnect TP sensor harness connector. See Fig 2 . Turn ignition on. Measure voltage between ground and TP sensor harness connector terminal No. 1. See Fig 1 . If voltage is about 5 volts, go to step  7 . If voltage is not about 5 volts, go to next step.

  6. Detect Malfunctioning Part

    Check the following:
    • Joint connector No. 2.
    • Harness for open or short between TP sensor and ECM.

    Repair as necessary. Perform appropriate DTC CONFIRMATION TEST to verify repair.

  7. Check Ground Circuit

    Turn ignition off. Check continuity between engine ground and TP sensor harness connector terminal No. 3. See Fig 1 . Continuity should exist. Also, check harness for short to power. If problem is found, go to next step. If problem is not found, go to step  9 .

  8. Detect Malfunctioning Part

    Check the following:
    • Joint connector No. 3.
    • Harness for open or short between TP sensor and ECM.
    • Harness for open or short between TP sensor and Transmission Control Module (TCM).

    Repair as necessary. Perform appropriate DTC CONFIRMATION TEST to verify repair.

  9. Check Input Signal Circuit

    Disconnect ECM harness connector. See Figure . Check continuity between TP sensor harness connector terminal No. 2 and ECM harness connector terminal No. 92. See Fig 1 . Continuity should exist. Also, check harness for short to ground and short to power. If problem is found, repair as necessary. Perform appropriate DTC CONFIRMATION TEST to verify repair. If problem is not found, go to next step.

  10. Check TP Sensor

    Reconnect all harness connectors. Start engine and warm to normal operating temperature. Turn ignition off. Remove vacuum hose connected to throttle opener. Using a hand vacuum pump, apply vacuum (more than 11.81 in. Hg) until throttle drum is not contacting throttle opener rod. Turn ignition on. Observe THRTL POS SEN voltage in DATA MONITOR mode with CONSULT-II. Or, measure voltage between ground and ECM terminal No. 92 (TP sensor signal) by backprobing. See THROTTLE POSITION SENSOR VOLTAGE  table. If voltage is as specified, go to next step. If voltage is not as specified, adjust closed TP switch and retest. See ON-VEHICLE ADJUSTMENTS article. If voltage is still not as specified, replace TP sensor. Perform appropriate DTC CONFIRMATION TEST to verify repair.

  11. Check MAF Sensor

    Reconnect all harness connectors. Start engine and warm to normal operating temperature. Check MAF sensor as shown in illustration. See Figure . If MAF sensor is okay, go to next step. If MAF sensor is not okay, replace MAF sensor. Perform appropriate DTC CONFIRMATION TEST to verify repair.

  12. Check CMP Sensor

    Check CMP sensor as shown in illustration. See Fig 3 . If CMP sensor is okay, go to next step. If CMP sensor is not okay, replace CMP sensor. Perform appropriate DTC CONFIRMATION TEST to verify repair.

  13. Check Fuel Injectors

    Disconnect injector harness connectors. Measure resistance between injector terminals. Resistance should be 13.5-17.5 ohms at 68°F (20°C). If resistance is as specified, go to next step. If resistance is not as specified, replace faulty injector(s). Perform appropriate DTC CONFIRMATION TEST to verify repair.

  14. Check For Intermittent

    Check for intermittent condition. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article. Perform appropriate DTC CONFIRMATION TEST to verify repair.
THROTTLE POSITION SENSOR VOLTAGE

Throttle Position Volts
Fully Closed .15-.85
Between Fully Closed & Fully Open .15-.85 To 3.5-4.7
Fully Open 3.5-4.7
Fig 1: TP Sensor Wiring Diagram
G00164600Courtesy of NISSAN MOTOR CO., U.S.A.
Fig 2: Locating TP Sensor & TP Switch Harness Connectors
G00014347Courtesy of NISSAN MOTOR CO., U.S.A.
Fig 3: Testing Camshaft Position Sensor
G00164601Courtesy of NISSAN MOTOR CO., U.S.A.
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