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Home >> Toyota >> 1999 >> Land Cruiser >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Self-Diagnostics >> Diagnostic Tests >> DTC P1120: Accelerator Pedal Position (App) Sensor Circuit >> Diagnosis & Repair (Using OBD-II Scan Tool)
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Diagnosis & Repair (Using OBD-II Scan Tool)

  1. Access ECM behind glove box. Turn ignition on. Using DVOM, backprobe ECM harness connector and measure voltage between terminals No. 2 (Blue/Red wire) and No. 18 (Brown/White wire) at ECM harness connector E6. 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/White wire) and No. 21 (Red wire) at ECM harness connector E6. With fully closed throttle, voltage should be .3-.9 volt. With fully open throttle, voltage should be 3.2-4.8 volts. Using DVOM, backprobe ECM harness connector and measure voltage between terminals No. 18 (Brown/White wire) and No. 9 (Red/Black wire) at ECM harness connector E6. 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 as specified, replace ECM. If voltage readings are not as specified, go to next step.
  3. Check APP sensor. See THROTTLE BODY under IDLE CONTROL SYSTEM in SYSTEM & COMPONENT TESTING - V6 & V8 article. If problem exists, replace APP sensor. If problem does not exist, repair open or short in wiring between ECM and APP sensor. See appropriate wiring diagram in WIRING DIAGRAMS article.
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