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Home >> Toyota >> 2001 >> 4Runner Base >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Self-Diagnostics >> Diagnostic Tests >> DTC P1120: Accelerator Pedal Position Sensor Circuit >> Diagnosis & Repair
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Diagnosis & Repair

  1. If using Toyota hand-held tester, go to next step. If Toyota hand-held tester is not available, go to step  3.
  2. Connect Toyota hand-held tester to Data Link Connector (DLC) No. 3. See Figure. Turn ignition on and then turn hand-held tester on. Using hand-held tester, monitor accelerator pedal position sensor voltages for VPA and VPA2 circuits with accelerator pedal depressed and released. See ACCELERATOR PEDAL POSITION SENSOR VOLTAGE  table. If voltages are not within specification, go to next step. If voltages are within specification, replace ECM. ECM is located behind glove box. See Figure.
    ACCELERATOR PEDAL POSITION SENSOR VOLTAGE

    Accelerator Pedal Position & Circuit Identification Volts
    Accelerator Pedal Depressed
    VPA Circuit 3.2-4.8
    VPA2 Circuit 4.7-5.1
    Accelerator Pedal Released
    VPA Circuit .3-.9
    VPA2 Circuit 1.8-2.7
  3. Remove glove box for access to ECM with electrical connectors still installed on ECM. See Figure. Turn ignition on. Using voltmeter, check voltage between terminals No. 11 (Blue/Black wire) and No. 25 (Green/Black wire) at ECM electrical connector E9 with all electrical connectors installed on ECM. See Figure. This is the E2 and VC terminals on ECM. Voltage should be 4.5-5.5 volts. If voltage is within specification, go to next step. If voltage is not within specification, replace ECM.
  4. Ensure ignition is still on. Using voltmeter, check voltage between terminal No. 11 (Blue/Black wire) at ECM electrical connector E9 and terminal No. 10 (Gray wire) at ECM electrical connector E11 with accelerator pedal released and with accelerator pedal depressed. See Figure. This is the E2 and VPA terminals on ECM. Also, check voltage between terminal No. 11 (Blue/Black wire) at ECM electrical connector E9 and terminal No. 15 (Blue wire) at ECM electrical connector E11 with accelerator pedal released and with accelerator pedal depressed. This is the E2 and VPA2 terminals on ECM. Ensure voltage is within specification. See ACCELERATOR PEDAL POSITION SENSOR VOLTAGE  table. If any voltage reading is not within specification, go to next step. If all voltage readings are within specification, replace ECM.
  5. Turn ignition off. Check accelerator pedal position sensor. See THROTTLE BODY under IDLE CONTROL SYSTEMS in SYSTEM & COMPONENT TESTING - V6 & V8 article. If accelerator pedal position sensor is okay, go to next step. If accelerator pedal position sensor is defective, replace throttle body with accelerator pedal position sensor as an assembly. See THROTTLE BODY under FUEL SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION - V6 & V8 article.
  6. Check for open and short in wiring harness and electrical connectors between accelerator pedal position sensor and ECM. See WIRING DIAGRAMS article. If wiring harness or electrical connector is defective, repair as necessary.
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