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Home >> Toyota >> 2004 >> Matrix Base, FWD, Automatic >> Repair and Diagnosis >> External Pages >> Different car >> Section 107 (Engine Controls - Self-Diagnostics) >> Diagnostic Tests >> DTC P2120, DTC P2122, DTC P2123, DTC P2125, DTC P2127, DTC P2128 Or DTC P2138 >> Diagnosis & Repair (Using OBD-II Scan Tool)
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Diagnosis & Repair (Using OBD-II Scan Tool)

WARNING: This page is about a different car, the 2003 Lexus GS 430. However, it is still accessible from the selected car via links, so may be relevant.
  1. Remove engine room ECM cover. Turn the ignition switch ON. Measure voltage between terminals VCPA and EPA, VPTK and EPTK of ECM connector E5. 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. Measure voltage between terminals VPA and EPTK, and VPA2 and EPA of ECM connector E5. See Figure. With pedal released, VPA voltage should be .5-1.1 volts and VPA2 voltage should be .9-2.3 volts. With pedal depressed, VPA voltage should be 3.0-4.6 volts and VPA2 voltage should be 3.4-5.0 volts. If okay, replace ECM. If not okay, go to next step.
  3. Check accelerator pedal position sensor. See THROTTLE SYSTEM OPERATION (GS430 & LS430) under THROTTLE BODY under THROTTLE CONTROLS in SYSTEM & COMPONENT TESTING - GS300, IS300, GS430, LS430 & SC430 article. Replace accelerator pedal position sensor as necessary. If okay, check for open and short in harness and connector in VCPA, VPTK, VPA, VPA2, EPTK and EPA circuits between ECM and accelerator pedal position sensor.
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