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.
1992 Lexus LS 400FACTORY OEM SERVICE PROCEDURE
Idle Speed Control (ISC) Valve
- Start engine. Idle engine for approximately 2 minutes. Turn engine off. Ensure a "clicking" sound is heard from ISC immediately after stopping engine.
- Disconnect ISC valve connector. Using a DVOM, check resistance between terminals specified in ISC VALVE RESISTANCE table. See Fig 1. If resistance is not as specified, replace ISC valve.ISC VALVE RESISTANCE
Terminals Ohms B1 & S1 Or S3 10-30 B2 & S2 Or S4 10-30
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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