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.
1990 Lexus ES 250 AutomaticFACTORY OEM SERVICE PROCEDURE
Fuel Cut System
- Start and warm engine to operating temperature. Ensure A/C is off. Connect a tachometer to engine. Disconnect Throttle Position Sensor (TPS) connector. Using a jumper wire, connect terminals IDL and E2 of harness connector. See Fig 1.
- Gradually raise engine speed. Observe tachometer as engine RPM is raised. RPM will fluctuate between fuel cut and fuel return points. See FUEL CUT RPM SPECIFICATIONS table.FUEL CUT RPM SPECIFICATIONS
Application RPM Fuel Cut 1800 Fuel Return 1200 - If fuel cut system does not function properly, ensure a clearance of .028" (.71 mm) is present between screw and lever on TPS. Ensure wiring harness is okay between TPS connector and ECU connector.
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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