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Home >> Infiniti >> 2001 >> G20 Base, Automatic, RE4F03W >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0120: Throttle Position (TP) Sensor >> Procedure

DTC P0120: Throttle Position (TP) Sensor: Procedure

  1. If malfunction "A" or "B" was duplicated, go to next step. If malfunction "C" was duplicated, adjust TP sensor. See ON-VEHICLE ADJUSTMENTS article. Check air intake duct and vacuum hoses for leaks or disconnection. Reconnect or repair as necessary and retest system. If no problems are found, go to next step.
  2. Turn ignition off. Loosen and retighten 2 engine ground bolts. See Figure. Disconnect TP sensor harness connector. See Fig 1. Turn ignition on. Measure voltage between ground and TP sensor harness connector terminal No. 3 (Pink/Blue 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. Retest system.
  3. Turn ignition off. Check continuity between engine ground and TP sensor harness connector terminal No. 1 (Black wire). Also check circuit for short to voltage. See WIRING DIAGRAMS article. Repair circuit as necessary and retest system. If ground circuit is okay, go to next step.
  4. Disconnect ECM harness connector. See Figure. Check continuity of Yellow wire between ECM harness connector terminal No. 92 and TP sensor harness connector terminal No. 2. See Figure. Also check circuit for short to ground and short to voltage. Repair circuit as necessary and retest system. If circuit is okay, go to next step.
    5. CAUTION: DO NOT use ECM ground terminals when measuring voltage.
  5. Reconnect all harness connectors. Start engine and warm to normal operating temperature. Turn ignition off. Disconnect vacuum hose from throttle opener. See Fig 2. Using a hand vacuum pump, apply vacuum to throttle opener until throttle opener rod does not contact throttle drum. Turn ignition on. Measure voltage between ground and ECM terminal No. 92 by backprobing, with throttle in specified positions. See THROTTLE POSITION (TP) SENSOR VOLTAGE  table. If voltage is as specified, go to next step. If voltage is not as specified, adjust TP sensor, if possible. See ON-VEHICLE ADJUSTMENTS article. If TP sensor can not be adjusted, replace TP sensor and retest system.
    6. CAUTION: DO NOT use ECM ground terminals when measuring voltage.
  6. If malfunction "B" was duplicated, go to step  9. If malfunction "A" or "C" was duplicated, ensure engine is at normal operating temperature. Measure voltage between ground and ECM terminal No. 61 (Blue wire) by backprobing, with engine at specified speeds. See MASS AIRFLOW SENSOR VOLTAGE  table. If voltage is as specified, go to next step. If voltage is not as specified, check for dust or foreign material in hot wire air passage of mass airflow sensor. If air passage is okay, replace mass airflow sensor and retest system.
    7. CAUTION: DO NOT use ECM ground terminals when measuring voltage.
  7. Start engine and warm to normal operating temperature. Measure voltage between engine ground and ECM terminals No. 66, 75 and 85 by backprobing, with engine at specified speeds. See PIN VOLTAGE CHARTS article. If voltage and waveforms are as specified, go to next step. If voltage and waveforms are not as specified, replace CMP sensor and retest system.
  8. Turn ignition off. Disconnect fuel injector harness connectors. Measure resistance between each injector terminals. Resistance should be 14-15 ohms at 68°F (20°C). If resistance is as specified on all injectors, go to next step. If resistance is not as specified, replace defective injector and retest system.
  9. Disconnect Blue, 12-pin Joint Connector (J/C) No. 1 (connector F-19). See Figure. Check continuity between ground and connector F-19 terminal No. 1 (Black wire). Also check circuit for short to voltage. See WIRING DIAGRAMS article. Repair circuit as necessary and retest system. If shield circuit is okay, go to next step.
  10. No problem is indicated at this time. Problem may be intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article.
THROTTLE POSITION (TP) SENSOR VOLTAGE

Throttle Position Volts
Fully Closed .15-.85
Partially Opened .15-.85 To 3.5-4.7
Fully Open 3.5-4.7
MASS AIRFLOW SENSOR VOLTAGE

Condition Volts
Key On, Engine Off Less Than 1.0
Engine Idling 1.3-1.7
2500 RPM 1.8-2.4
Idle To 4000 RPM (1) 1.3-1.7 To About 4.0
(1) Voltage should rise in proportion to engine speed.
Fig 1: Locating TP Sensor Harness Connector
G00010124Courtesy of NISSAN MOTOR CO., U.S.A.
Fig 2: Locating EGR System Components, IACV-AAC Valve & Throttle Opener
G00010144Courtesy of NISSAN MOTOR CO., U.S.A.
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