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Home >> Nissan-Datsun >> 2004 >> Sentra SE-R Spec V >> Repair and Diagnosis >> External Pages >> Different car >> Section 70 (Engine Controls - Self-Diagnostics) >> Diagnostic Tests >> DTC P0121: Throttle Position Sensor Circuit Range/Performance, DTC P0122: Throttle Position Sensor Circuit Low Input Or DTC P0123: Throttle Position Sensor Circuit High Input >> Diagnostic Procedure
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Diagnostic Procedure

WARNING: This page is about a different car, the 2002 Nissan Xterra and 2002 Nissan Frontier. However, it is still accessible from the selected car via links, so may be relevant.
  1. If malfunction "A" or "B" was duplicated, go to next step. If malfunction "C" was duplicated, adjust TP sensor by performing BASIC INSPECTION. See ON-VEHICLE ADJUSTMENTS article. Check air intake duct and vacuum hoses for leaks or disconnection. If problem is found, repair as necessary. If problem is not found, go to next step.
  2. Turn ignition off. Loosen and retighten engine ground bolts. See Figure or Figure . Disconnect TP sensor harness connector. See Fig 1 or Fig 2 . Turn ignition on. On 2.4L models, go to next step. On 3.3L models, go to step  5 .
  3. Measure voltage between ground and TP sensor harness connector terminal No. 1 (Brown wire). If voltage is about 5 volts, go to next step. If voltage is not about 5 volts, repair open or short between ECM and TP sensor.
  4. Turn ignition off. Check continuity between engine ground and TP sensor harness connector terminal No. 3 (Black/White wire). Continuity should exist. Also, check circuit for short to voltage. If problem is found, repair as necessary. If problem is not found, go to step  7 .
  5. Measure voltage between ground and TP sensor harness connector terminal No. 3 (Black/White wire). If voltage is about 5 volts, go to next step. If voltage is not about 5 volts, repair open or short between ECM and TP sensor.
  6. Turn ignition off. Check continuity between engine ground and TP sensor harness connector terminal No. 1 (Brown wire). Continuity should exist. Also, check circuit for short to voltage. If problem is found, repair as necessary. If problem is not found, go to next step.
  7. Disconnect ECM harness connector. See Figure or Figure . Check continuity of Blue wire between ECM harness connector terminal No. 23 and TP sensor harness connector terminal No. 2. See Figure . Also, check circuit for short to ground and short to voltage. If problem is found, repair as necessary. If problem is not found, go to next step.
  8. Reconnect all harness connectors. Start engine and warm to normal operating temperature. Turn engine off. Turn ignition on. If using CONSULT-II, go to next step. If not using CONSULT-II, go to step  10 .
  9. Select DATA MONITOR mode with CONSULT-II. Observe THRTL POS SEN reading on CONSULT-II with throttle in specified positions. See appropriate TP SENSOR VOLTAGE table. If voltage is as specified, go to step  11 . If voltage is not as specified, adjust TP sensor by performing BASIC INSPECTION. See ON-VEHICLE ADJUSTMENTS article. If voltage is still not as specified, replace TP sensor.
    10. CAUTION: DO NOT use ECM ground terminals when measuring voltage.
  10. Measure voltage between ground and ECM terminal No. 23 (TP sensor signal) by backprobing, with throttle in specified positions. See appropriate TP SENSOR VOLTAGE table. If voltage is as specified, go to next step. If voltage is not as specified, adjust TP sensor by performing BASIC INSPECTION. See ON-VEHICLE ADJUSTMENTS article. If voltage is still not as specified, replace TP sensor.
    11. CAUTION: DO NOT use ECM ground terminals when measuring voltage.
  11. Reconnect all harness connectors. Start engine and warm to normal operating temperature. Measure voltage between ground and ECM terminal No. 54 by backprobing, with engine at specified speeds. See appropriate MASS AIRFLOW SENSOR VOLTAGE table under DIAGNOSTIC PROCEDURE under DTC P0101, DTC P0102 OR DTC P0103: MASS AIRFLOW SENSOR. If voltage is as specified, go to step  13 . If voltage is not as specified, go to next step.
  12. Turn ignition off. Disconnect and reconnect MAF sensor harness connector. Repeat step  11 . If voltage is still not as specified, remove MAF sensor. Check hot film for damage or dust. If problem is found, clean or replace MAF sensor as necessary. If problem is not found, go to next step.
    13. CAUTION: DO NOT use ECM ground terminals when measuring voltage.
  13. Start engine and warm to normal operating temperature. Measure voltage between ground and ECM terminals No. 44, 48 and 49 (CMP sensor signal) by backprobing, with engine at specified speeds. See PIN VOLTAGE CHARTS article. If voltage or waveforms are as specified, go to next step. If voltage or waveforms are not as specified, replace CMP sensor.
  14. Turn ignition off. Disconnect injector harness connectors. Measure resistance between injector terminals. Resistance should be 10-14 ohms at 77°F (25°C). If resistance is as specified, go to next step. If resistance is not as specified, replace fuel injector.
  15. Turn ignition off. Disconnect Gray, 6-pin joint connector No. 2 (connector F32) located near ECM. See Figure , Figure or Figure . Check the following:
    • Check continuity between ground and connector F32 terminal No. 1 (Black/Yellow wire).
    • Check continuity between each joint connector terminal (component side).

    Continuity should exist. Also, check circuit for short to voltage. If problem is found, repair as necessary. If problem is not found, go to next step.

  16. No problem is indicated at this time. Problem may be intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article.
TP SENSOR VOLTAGE (2.4L)

Throttle Position Volts
Fully Closed .2-.8
Partially Open .2-.8 To 3.5-4.5
Fully Open 3.5-4.5
TP SENSOR VOLTAGE (3.3L)

Throttle Position Volts
Fully Closed .15-.85
Partially Open .15-.85 To 3.5-4.7
Fully Open 3.5-4.7
Fig 1: Locating TP Sensor Harness Connector (2.4L)
G00147162Courtesy of NISSAN MOTOR CO., U.S.A.
Fig 2: Locating TP Sensor Harness Connector (3.3L)
G99H51885Courtesy of NISSAN MOTOR CO., U.S.A.
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