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.
1998 Lexus SC 400FACTORY OEM SERVICE PROCEDURE
Variable Valve Timing (VVT) System Operation
- Start and run engine. Allow engine to reach normal operating temperature. Disconnect suspect Oil Control Valve (OCV) connector. Connect fused jumper wires between positive battery terminal and suspect OCV connector terminal No. 1, and negative battery terminal and OCV connector terminal No. 2. See Figure.
- If engine speed does not change with OCV disconnected and changes (rough idle) with fused jumper wires connected, system is okay. If results are not as specified, check OCV. See CAMSHAFT TIMING OIL CONTROL VALVE . If OCV is okay, check VVT pulley. See DTC P1349 test in TESTS W/CODES article. If VVT pulley is okay, check wiring to OCV and ECM. See WIRING DIAGRAMS article.
Factory Service Tools
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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.
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