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Home >> Nissan-Datsun >> 2003 >> Sentra Limited >> Repair and Diagnosis >> External Pages >> Different car >> Section 204 (Engine Controls - Self-Diagnostics - 1.8L - Ca) >> Diagnostic Tests >> DTC P0121, DTC P0122 Or DTC P0123: Throttle Position (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.
  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 engine ground bolts located on intake manifold. See Figure . Disconnect TP sensor harness connector. See Fig 1 . Turn ignition on. Measure voltage between ground and terminal No. 1 (Red wire) at TP sensor harness connector. See Fig 3 . If voltage is about 5 volts, go to next step. If voltage is not about 5 volts, repair open or short in Red wire between TP sensor and PCM and retest system.
  3. Turn ignition off. Check continuity of Black wire between TP sensor harness connector terminal No. 3 and ground. Continuity should exist. Also check circuit for short to voltage. If problem exist, repair as necessary and retest system. If problem does not exist, go to next step.
  4. Turn ignition off. Disconnect PCM harness connector. See Figure . Check continuity of Yellow wire between terminal No. 92 at PCM harness connector and terminal No. 2 at TP sensor harness connector. See Figure and Fig 3 . Continuity should exist. Also check circuit for short to ground and short to voltage. If problem exists, repair as necessary and retest system. If problem does not exist, go to next step.
  5. Reconnect all harness connectors. Start engine and warm to normal operating temperature. Stop engine and turn ignition on. Disconnect vacuum hose from throttle opener. Connect a hand-held vacuum pump to throttle opener vacuum port. Apply 11.81 in. Hg. Using a DVOM, backprobe PCM harness connector and measure voltage between ground and terminal No. 92 (Yellow wire) at PCM harness connector, with throttle in specified positions. See THROTTLE POSITION (TP) SENSOR VOLTAGE  table. If voltage is not as specified, go to next step. If voltage is as specified, go to step  7 .
  6. Adjust closed throttle position switch. See ON-VEHICLE ADJUSTMENTS article. Repeat step  5 . If voltage is now as specified, go to next step. If voltage is still not as specified, replace TP sensor and retest system.
  7. If malfunction "A" or "C" was duplicated, go to step  12 . If malfunction "B" was duplicated, go to next step.
  8. Start engine and warm to normal operating temperature. Using a DVOM, backprobe PCM harness connector and measure voltage between ground and terminal No. 61 (Green wire) at PCM harness connector (MAF sensor signal), with engine at specified speeds. See MASS AIRFLOW SENSOR VOLTAGE  table under DTC P0101: MASS AIRFLOW (MAF) SENSOR. Go to next step.
  9. If voltage is as specified, go to next step. If voltage is not as specified, disconnect and reconnect MAF sensor harness connector and repeat step  8 . If voltage is still not as specified, replace MAF sensor and retest system. If voltage is now as specified, go to next step.
  10. Ensure engine is at normal operating temperature. Using a DVOM, backprobe PCM harness connector. Backprobe between ground and terminals No. 66 and 75 (both Red wires) at PCM harness connector. Voltage should be about 2-3 volts at idle and 2000 RPM. For waveforms, see PIN VOLTAGE CHARTS article. If voltages or waveforms are as specified, go to next step. If voltages or waveforms are not as specified, replace camshaft position sensor and retest system.
  11. Turn ignition off. Disconnect fuel injector harness connector. Measure resistance between fuel injector terminals (component side). 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 defective fuel injector(s) as necessary and retest system.
  12. No problem is indicated at this time. Problem may be intermittent. See TESTING PROCEDURE  .
THROTTLE POSITION (TP) SENSOR VOLTAGE

Throttle Position Volts
Fully Closed 0.15-0.85
Between Fully Closed & Fully Open 0.86-3.4
Fully Open 3.5-4.7
Fig 1: Locating Throttle Position (TP) Sensor & TP Switch Harness Connectors
G00014347Courtesy of NISSAN MOTOR CO., U.S.A.
Fig 2: Identifying Throttle Position (TP) Sensor & TP Switch Terminals (Component Side Shown)
G00014348Courtesy of NISSAN MOTOR CO., U.S.A.
Fig 3: Throttle Position Sensor Circuit Wiring Diagram
G00274263Courtesy of NISSAN MOTOR CO., U.S.A.
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