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Home >> Toyota >> 2000 >> RAV4 Base, FWD, Automatic >> Repair and Diagnosis >> External Pages >> Different car >> Section 17 (Engine Control System Self-Diagnostics) >> Diagnostic Tests >> DTC P0120: Throttle Position (TP) Sensor Circuit >> Diagnosis & Repair
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Diagnosis & Repair

WARNING: This page is about a different car, the 2000 Toyota Corolla. However, it is still accessible from the selected car via links, so may be relevant.
  1. Connect scan tool to Data Link Connector (DLC) No. 3. See Figure. Turn ignition on. Using scan tool, monitor throttle valve opening percentage. Opening percentage should be approximately 10 percent with fully closed throttle, and should be approximately 80 percent with throttle fully open (WOT). If percentages are as specified, problem is intermittent. Check component and ECM connections. If percentages are not as specified, go to next step.
  2. Turn ignition off. Disconnect TP sensor harness connector. Turn ignition on. Using DVOM, measure voltage between ground and terminal No. 1 (Yellow wire) at TP sensor harness connector. If voltage is 4.5-5.5 volts, go to next step. If voltage is not 4.5-5.5 volts, go to step  5.
  3. Check TP sensor. See ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING - 4-CYLINDER article. If problem exists, replace TP sensor. If problem does not exist, go to next step.
  4. Access ECM below stereo, behind instrument panel, just in front of center console. Turn ignition on. Using DVOM, backprobe ECM harness connector. On models with 4A/T transmission, measure voltage between terminals No. 18 (Brown wire) and No. 23 (Light Green wire) at ECM harness connector E8. See Figure. On models without 4A/T transmission, measure voltage between terminals No. 9 (Brown wire) and No. 11 (Light Green wire) at ECM harness connector E5. See Figure. On all models, voltage should be .3-.8 volt with throttle fully closed and 3.2-4.9 volts with throttle fully open (WOT). If voltage is as specified, replace ECM. If voltage is not as specified, repair open or short in wiring between TP sensor and ECM. See WIRING DIAGRAMS article.
  5. Access ECM below stereo, behind instrument panel, just in front of center console. Turn ignition on. Using DVOM, backprobe ECM harness connector. On models with 4A/T transmission, measure voltage between terminals No. 2 (Yellow wire) and No. 18 (Brown wire) at ECM harness connector E8. See Figure. On models without 4A/T transmission, measure voltage between terminals No. 1 (Yellow wire) and No. 9 (Brown wire) at ECM harness connector E5. See Figure. On all models, voltage should be 4.5-5.5 volts. If voltage is as specified, repair open in Yellow wire between TP sensor and ECM. If voltage is not as specified, replace ECM.
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