Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSTOYOTA2004MATRIX XR, FWD, STANDARDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 19 (ENGINE CONTROL SYSTEM SELF-DIAGNOSTICS)DIAGNOSTIC TESTSDTC P0120: THROTTLE POSITION SENSOR CIRCUITDIAGNOSIS & REPAIR
2004 Toyota Matrix XR, FWD, Standard
Diagnosis & Repair
2004 Toyota Matrix XR, FWD, StandardSECTION Diagnosis & Repair
WARNING: This page is about a different car, the 2002 Toyota Sequoia. However, it is still accessible from the selected car via links, so may be relevant.
- If Toyota hand-held tester is available, go to next step. If Toyota hand-held tester is not available, go to step 4.
- Connect hand-held tester to Data Link Connector (DLC) No. 3 at driver's side of instrument panel. See Figure. Turn ignition on and then turn hand-held tester on.
- Using hand-held tester, monitor throttle valve opening for VTA and VTA2 circuits with accelerator pedal released and with accelerator pedal depressed. VTA circuit is displayed as a percentage and VTA2 circuit is displayed as a voltage. With accelerator pedal released, VTA circuit should be 8-20 percent and VTA2 circuit should be 2.0-2.9 volts. With accelerator pedal depressed, VTA circuit should be 64-96 percent and VTA2 circuit should be 4.7-5.1 volts. If throttle valve opening readings are not within specification, go to next step. If throttle valve opening readings are within specification, replace ECM. ECM is located behind glove box and heater duct. See Figure.
- Remove glove box and heater duct (if necessary) 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 (Green/Black wire) and No. 18 (Green/White wire) at ECM electrical connector E7. See Figure. This is the VC and E2 terminals on ECM. Voltage should be 4.5-5.5 volts. If voltage is specification, go to next step. If voltage is not within specification, replace ECM.
- Ensure ignition is still on. Using voltmeter, check voltage between terminals No. 13 (Black/Yellow wire) and No. 18 (Green/White wire) at ECM electrical connector E7 with accelerator pedal released and with accelerator pedal depressed. See Figure. This is the VTA and E2 terminals on ECM. Also, check voltage between terminals No. 18 (Green/White wire) and No. 20 (Pink/Blue wire) at ECM electrical connector E7 with accelerator pedal released and with accelerator pedal depressed. This is the E2 and VTA2 terminals on ECM. Ensure voltage is within specification. See TP SENSOR VOLTAGE SPECIFICATIONS AT ECM table. If any voltage reading is not within specification, go to next step. If all voltage readings are within specification, replace ECM.TP SENSOR VOLTAGE SPECIFICATIONS AT ECM
Accelerator Pedal Position & Terminals Volts Accelerator Pedal Released VTA & E2 .4-1.0 VTA2 & E2 2.0-2.9 Accelerator Pedal Depressed VTA & E2 3.2-4.8 VTA2 & E2 4.7-5.1 - Turn ignition off. Check TP sensor. See THROTTLE BODY under IDLE CONTROL SYSTEMS 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 BODY under FUEL SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION - V6 & V8 article.
- Check for open and short in wiring harness and electrical connectors between TP sensor and ECM. See WIRING DIAGRAMS article. If wiring harness or electrical connector is defective, repair as necessary.
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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.