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Diagnosis & Repair

  1. Connect Toyota hand-held tester or scan tool to Data Link Connector (DLC) No. 3. See Figure. Turn ignition on and then turn hand-held tester or scan tool on.
  2. Using hand-held tester or scan tool, read throttle valve opening percentages with throttle fully closed and fully open. Throttle valve opening percentage should be approximately 10 percent with throttle fully closed and approximately 75 percent with throttle fully open. If throttle valve opening percentages are not within specification, go to next step. If throttle valve opening percentages are within specification, problem is intermittent. Check for defective connections or intermittent problem in wiring between TP sensor and ECM. ECM is located at passenger's side of instrument panel, just below glove box. See Figure.
  3. Turn ignition off. Disconnect electrical connector at TP sensor. Turn ignition on. Using voltmeter, check voltage between body ground and terminal No. 1 (Yellow wire) at electrical connector for TP. If voltage is 4.5-5.5 volts, go to next step. If voltage is not 4.5-5.5 volts, go to step  6.
  4. Check TP sensor. See THROTTLE POSITION SENSOR under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING - V6 & V8 article. If TP sensor is okay, go to next step. If TP sensor is defective, replace TP sensor. See THROTTLE POSITION SENSOR under ENGINE SENSORS & SWITCHES in REMOVAL, OVERHAUL & INSTALLATION - V6 & V8 article.
  5. 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. 18 (White wire) and No. 23 (Blue/White wire) at ECM electrical connector E11 with all electrical connectors installed on ECM with throttle fully closed and fully open. See Figure. This is the E2 and VTA1 terminals on ECM. Voltage should be .3-1.0 volt with throttle fully closed and 2.7-5.2 volts with throttle fully open. If voltages are within specification, replace ECM. If voltages are not within specification, repair open or short in wiring harness and electrical connectors between TP sensor and ECM. See WIRING DIAGRAMS article.
  6. Remove glove box for access to ECM with electrical connectors still installed on ECM. See Figure. Ensure ignition is on. Using voltmeter, check voltage between terminals No. 2 (Yellow wire) and No. 18 (White wire) at ECM electrical connector E11 with all electrical connectors installed on ECM with throttle fully closed and fully open. See Figure. This is the VC and E2 terminals on ECM. Voltage should be 4.5-5.5 volts. If voltage is not within specification, replace ECM. If voltage is within specification, repair open in Yellow wire and electrical connectors between TP sensor and ECM. See WIRING DIAGRAMS article.
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