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.
Diagnosis & Repair
2004 Toyota Matrix XR, FWD, StandardSECTION Diagnosis & Repair
WARNING: This page is about a different car, the 2002 Toyota Tundra. However, it is still accessible from the selected car via links, so may be relevant.
- Connect Toyota hand-held tester or scan tool 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 or scan tool on.
- 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 behind glove box and heater duct. See Figure.
- Turn ignition off. Disconnect electrical connector at TP sensor. Turn ignition on. Using voltmeter, check voltage between body ground and terminal No. 2 (Green/Black 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.
- 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.
- Remove glove box and heater duct (if necessary) for access to ECM with electrical connectors still installed on ECM. See Figure. Turn ignition on. Using voltmeter, check voltage between terminals No. 18 (Green/White wire) and No. 23 (Black/Yellow wire) at ECM electrical connector E6 with all electrical connectors installed on ECM with throttle fully closed and fully open. See Figure. This is the E2 and VTA 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 Black/Yellow wire and electrical connectors between TP sensor and ECM. See WIRING DIAGRAMS article.
- 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 E6 with all electrical connectors installed on ECM. 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 Green/Black wire and electrical connectors between TP sensor and ECM. See WIRING DIAGRAMS article.
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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.