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Home >> Suzuki >> 2002 >> Esteem GL, 4D Sedan, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics - 1.6L >> Diagnostic Tests >> DTC P0121: Throttle Position Sensor Circuit - Range/Performance Problem >> Diagnosis & Repair Procedure
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Diagnosis & Repair Procedure

  1. If engine system check has been performed, go to next step. If engine system check has not been performed, go to A4: ENGINE SYSTEM CHECK  under SYSTEM TESTS.
  2. Check for DTCs. See RETRIEVING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. If DTC P1450 and/or P1451 is also set, repair those DTCs first. See DTC P1450 OR DTC P1451  . If DTC P1450 and/or P1451 is not set, go to next step.
  3. If scan tool is not available, go to next step. If scan tool is available, turn ignition on. Using scan tool, observe and note TP sensor output voltage with throttle valve at completely closed and open positions. Voltage reading should be 0.2-1 volts with throttle valve at closed position and 2.8-4.8 volts with throttle valve at open position. If output voltage is not as specified, go to step  5 . If output voltage is as specified, substitute a known good ECM, and repeat DTC CONFIRMATION TEST  .
  4. Turn ignition on. Backprobing at ECM, measure voltage between ground and ECM 16-pin connector C20 terminal No. 6 (Gray wire) with throttle valve at completely closed and open positions. See Figure . Voltage reading should be 0.2-1 volts with throttle valve at closed position and 2.8-4.8 volts with throttle valve at open position. If voltage reading as specified, go to next step. If voltage reading is not as specified, check for poor terminal contact at ECM 16-pin connector C20. If problem is found, repair as necessary. After repair, repeat DTC CONFIRMATION TEST  . If no problem is found, substitute a known good ECM, and repeat DTC CONFIRMATION TEST  .
  5. Turn ignition off. Disconnect TP sensor 3-pin harness connector. Check for poor terminal contact at TP sensor connector. If problem is found, repair as necessary. After repair, repeat DTC CONFIRMATION TEST  . If no problem is found, leave harness connector disconnected and go to next step.
  6. Measure resistance between specified TP sensor terminals. See CHECKING THROTTLE POSITION SENSOR RESISTANCE  table. See Fig 1 . If resistance is as specified, go to next step. If resistance is not as specified, replace TP sensor. After repair, repeat DTC CONFIRMATION TEST  .
    CHECKING THROTTLE POSITION SENSOR RESISTANCE

    Measure Between Terminals Specification (Ohms)
    No. 1 & 2 2,500-6,000
    No. 1 & 3 (1) 100-20,000
    (1) Should vary with throttle position.
  7. Check for high resistance in specified circuits between TP sensor and ECM. See CHECKING THROTTLE POSITION SENSOR CIRCUITS  table. See Fig 1 . If problem is found, repair as necessary. If no problem is found, substitute a known good ECM, and repeat DTC CONFIRMATION TEST  .
    CHECKING THROTTLE POSITION SENSOR CIRCUITS

    TP Sensor Terminal No. ECM Terminal No. Wire Color
    1 C20-9 Green/Red
    2 C20-1 Pink
    3 C20-6 Gray
Fig 1: Testing Throttle Position Sensor
G98A12336Courtesy of SUZUKI OF AMERICA CORP.
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