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.

1997 Lexus LS 400FACTORY OEM SERVICE PROCEDURE

Idle Air Control Valve

IDLE AIR CONTROL (IAC) VALVE RESISTANCE

Application

Ohms

LS400 ⁽³⁾

Cold ⁽¹⁾

31-61

Hot ⁽²⁾

38-71

⁽¹⁾	IAC valve temperature of 14-122°F (-10-50°C).

⁽²⁾	IAC valve temperature of 123-212°F (51-100°C).

⁽³⁾	Measure resistance between terminal B1 and terminals S1 and S3. Also, measure resistance between terminal B2 and terminals S2 and S4. See Fig 1.

Fig 1: Identifying IAC Valve Terminals

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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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