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Home >> Toyota >> 2000 >> Tundra Limited, 4WD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Self-Diagnostics - V8 >> Diagnostic Tests >> DTC P0120: Throttle Position (TP) 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 E6 and measure voltage between terminals No. 2 (Green/Black wire) and No. 18 (Green/White wire). 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 E6 and measure voltage between terminals No. 13 (Black/Yellow wire) and No. 18 (Green/White wire). With fully closed throttle, voltage should be .4-1.0 volt. With fully open throttle, voltage should be 3.2-4.8 volts. Using DVOM, backprobe ECM harness connector E6 and measure voltage between terminals No. 18 (Green/White wire) and No. 20 (Pink/Blue wire). With fully closed throttle, voltage should be 2.0-2.9 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 Throttle Position (TP) sensor. See THROTTLE BODY under IDLE CONTROL SYSTEMS in SYSTEM & COMPONENT TESTING - V6 & V8 article. If problem exists, replace TP sensor. If problem does not exist, check for an open or short in wiring between ECM and TP sensor. See WIRING DIAGRAMS article. Repair wiring harness as necessary.
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