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 38 (ENGINE CONTROLS - SELF-DIAGNOSTICS)DIAGNOSTIC TESTSDTC P1656: OIL CONTROL VALVE (OCV) CIRCUIT MALFUNCTIONDIAGNOSIS & REPAIR (USING LEXUS SCAN TOOL)
2004 Toyota Matrix XR, FWD, Standard
Diagnosis & Repair (Using Lexus Scan Tool)
2004 Toyota Matrix XR, FWD, StandardSECTION Diagnosis & Repair (Using Lexus Scan Tool)
WARNING: This page is about a different car, the 2002 Lexus IS 300. However, it is still accessible from the selected car via links, so may be relevant.
- Start and run engine. Allow engine to reach normal operating temperature. Connect Lexus scan tool to Data Link Connector (DLC) No. 3. See Figure. Select VVT from scan tool ACTIVE TEST menu. Using scan tool, turn OCV on and off. If idle speed is normal with OCV off and engine idles rough or stalls when OCV is on, VVT is functioning properly at this time. Fault is intermittent. DTC may have been set because of a foreign object that was temporarily caught in engine oil system but after a short time system returned to normal. If idle speed does not function as specified, go to next step.
- With engine running. Disconnect OCV connector and note idle speed. Engine idle speed should not change. Connect fused jumper wires between positive battery terminal and OCV connector terminal No. 1, and negative battery terminal and OCV connector terminal No. 2. See Figure. Engine should idle rough or stall. If OCV operates as specified, go to next step. If OCV does not operate as specified, replace OCV.
- Access ECM under protective cover, behind left headlight in engine compartment. Backprobe ECM E7 connector. Start engine. Backprobing, connect oscilloscope between ECM E7 connector terminals No. 5 (Yellow/Black wire) and No. 6 (Red/Yellow wire). See Figure. Ensure waveform pattern is as illustrated. See Figure. Slowly increase engine speed. Waveform frequency "A" should lengthen as engine speed increases. If waveform pattern is as shown, go to next step. If waveform pattern is not as shown, replace ECM.
- Check for an open or short circuit and connector in wire harness between OCV and ECM E7 connector. Repair as necessary. If circuit and connector are okay, problem is intermittent.
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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.