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Home >> Toyota >> 2001 >> MR2 C56 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Self-Diagnostics >> Diagnostic Tests >> DTC P1120: Accelerator Pedal Position Sensor Circuit >> Diagnosis & Repair (Using OBD-II Scan Tool)
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Diagnosis & Repair (Using OBD-II Scan Tool)

  1. Access ECM on driver's side of firewall behind driver's seat, luggage compartment lids and partition board. See Figure. Turn ignition on. Using DVOM, backprobe ECM harness connector and measure voltage between terminals No. 2 (Blue/Red wire) and No. 18 (Brown wire) at ECM harness connector E4. See Figure. If voltage is 4.5-5.5 volts, go to next step. If voltage is not 4.5-5.5 volts, replace ECM.
  2. Using DVOM, backprobe ECM harness connector and measure voltage between terminals No. 18 (Brown wire) and No. 20 (Blue wire) at ECM harness connector E6. With fully closed throttle, voltage should be .3-.9 volt. With fully open throttle, voltage should be 3.2-4.7 volts. Using DVOM, backprobe ECM harness connector and measure voltage between terminals No. 18 (Brown wire) and No. 19 (Red/Black wire) at ECM harness connector E4. With fully closed throttle, voltage should be 1.8-2.7 volts. With fully open throttle, voltage should be 4.7-5.1 volts. If voltage readings are not as specified, go to next step. If voltage readings are as specified, replace ECM.
  3. Check APP sensor. See THROTTLE BODY under IDLE CONTROL SYSTEMS in SYSTEM & COMPONENT TESTING - 4-CYLINDER article. If problem exists, replace APP sensor. If problem does not exist, repair open or short in wiring between ECM and APP sensor. See WIRING DIAGRAMS article.
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