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HOMESERVICE MANUALSTOYOTA2004MATRIX XR, FWD, STANDARDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 471 (ENGINE CONTROLS - DIAGNOSTICS)CIRCUIT INSPECTIONDTC P2121: THROTTLE/PEDAL POSITION SENSOR/SWITCH "D" CIRCUIT RANGE/PERFORMANCEINSPECTION PROCEDUREOBD II SCAN TOOL (EXCLUDING HAND HELD TESTER)
2004 Toyota Matrix XR, FWD, Standard

OBD II scan tool (excluding hand held tester)

2004 Toyota Matrix XR, FWD, StandardSECTION OBD II scan tool (excluding hand held tester)
WARNING: This page is about a different car, the 2004 Toyota RAV4. However, it is still accessible from the selected car via links, so may be relevant.
  1. Check voltage between terminals VPA and EPA, and VPA2 and EPA2 of ECM connector. 

    PREPARATION: 

    1. Remove the glove compartment (see COMPONENTS ).
    2. Turn the ignition switch ON.

    CHECK: 

    Measure the voltage between terminals VPA and EPA, and VPA2 and EPA2 of the ECM connector.

    OK: 

    ACCELERATOR PEDAL VOLTAGE

    Accelerator Pedal Voltage
    Accelerator Pedal VPA - EPA VPA2 - EPA2
    Released 0.5 to 1.1 V 1.5 to 2.9 V
    Depressed 2.5 to 4.6 V 3.9 to 5.5 V
    Fig 1: Checking Voltage Between Terminals VPA (+) And EPA (-), And VPA2 (+) And EPA2 (-)
    G02912598Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. OK : Replace ECM (see  COMPONENTS  ).  
    2. NG : Go to next step. 
  2. Check for open and short in wire harness in VCPA, VCP2, VPA, VPA2, EPA and EPA2 circuits between ECM and accelerator pedal position sensor (see  HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION PROCEDURE  in INTRODUCTION article).  
    1. OK : Repair or replace. 
    2. NG : Replace accelerator pedal assembly (see  SFI  article). 
RENDER: 1.0x

NO RELATED

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.