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Home >> Suzuki >> 2001 >> Vitara JS, 4D Utility, Standard >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0121: Throttle Position (TP) Sensor Circuit Performance Problem >> Diagnosis & Repair Procedure
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Diagnosis & Repair Procedure

  1. Perform DTC CONFIRMATION TEST . If DTC P0121 is set, go to next step. If DTC P0121 is not set, problem is intermittent. System is okay at this time. See TROUBLE SHOOTING - NO CODES article.
  2. Check for DTC P0122 or P0123. See RETRIEVING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. If DTCs P0122 and P0123 are not set, go to next step. If DTC P0122 or P0123 is set go to appropriate test. See DTC P0122: THROTTLE POSITION (TP) SENSOR CIRCUIT, LOW INPUT  or DTC P0123: THROTTLE POSITION (TP) SENSOR CIRCUIT, HIGH INPUT  .
  3. If using scan tool, go to next step. If not using scan tool, turn ignition on. Backprobing, measure voltage between ground and PCM 26-pin connector C51-3 terminal No. 9. See Figure. With throttle closed, voltage should be .5-1.2 volts. With throttle fully opened, voltage should be 3.4-4.7 volts. If voltage is not as specified, go to step  5. If voltage is as specified, disconnect PCM 26-pin connector C51-3. Check for poor terminal contact at PCM 26-pin connector C51-3. If poor terminal contact is found, repair as necessary and go to DTC CONFIRMATION TEST . If terminal contact is okay, replace PCM and go to DTC CONFIRMATION TEST .
  4. Turn ignition off. Connect scan tool. Turn ignition on. Select TP sensor parameter on scan tool. Reading on scan tool with throttle closed, should be .5-1.2 volts. Reading on scan tool with throttle fully opened, should be 3.4-4.7 volts. If voltage is not as specified, go to next step. If readings are as specified, replace PCM and go to DTC CONFIRMATION TEST .
  5. Turn ignition off. Disconnect TP sensor connector. Check for poor terminal contact at TP sensor connector. If poor terminal contact is found, repair as necessary and go to DTC CONFIRMATION TEST . If terminal contact is okay, go to next step.
  6. Check TP sensor operation. See SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING article. Replace as necessary. If TP sensor operation is okay, check for high resistance in Gray/Red, Red/Green or Gray/Yellow wire between TP sensor and PCM 26-pin connector C51-3 terminals No. 13, No. 9 and No. 21. If wires are okay, replace PCM and go to DTC CONFIRMATION TEST .
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