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
Engine Controls - System/Component Tests
- Introduction
- Testing - Preliminary Information
- Computerized Engine Controls
- Es250 Control Unit
- Engine Sensors & Switches
- Circuit Opening Relay
- EFI Main Relay
- Fuel Pump & Fuel Pressure Regulator
- Fuel Cut System
- Fuel Injectors
- Fuel Pressure Control System
- Idle Speed Control (ISC) Valve
- EGR System
- Dashpot
- Miscellaneous Controls
- Cold Start System
- Theft Deterrent System Ignition Switch Circuit Test
- Theft Deterrent System Key Unlock Warning Switch Circuit
- Theft Deterrent System Starter Cut System Circuit
- Transmission
Factory Service Tools
Use the Manual With the Right Hardware
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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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