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.
1999 Lexus SC 400FACTORY OEM SERVICE PROCEDURE
Engine Controls - System & Component Testing
- Introduction
- Air Induction Systems
- Computerized Engine Controls
- Engine Sensors & Switches
- Accelerator Pedal Position Sensor
- Camshaft Position Sensor
- Crankshaft Position Sensor
- Engine Coolant Temperature (ECT) Sensor
- Heated Oxygen Sensor Heater Resistance
- Heated Oxygen Sensor Operation
- Intake Air Temperature (IAT) Sensor
- Knock Sensor
- Mass Airflow (MAF) Sensor
- Park/Neutral Position (PNP) Switch
- Park/Neutral Position (PNP) Switch Circuit
- Throttle Position (TP) Sensor
- Vapor Pressure Sensor
- Variable Valve Timing Sensor
- Vehicle Speed Sensor (VSS)
- Motors, Relays & Solenoids
- Fuel System
- Fuel Delivery
- Notes
- Fuel Pump Operation (Using Battery Voltage) - GS300 & GS400
- Fuel Pump Operation (Using Battery Voltage) - LS400, SC300 & SC400
- Fuel Pump Resistance (GS300 & GS400)
- Fuel Pump Resistance (LS400, SC300 & SC400)
- Fuel Pump Control Circuit (GS300 & GS400)
- Fuel Pump Control Circuit (LS400)
- Fuel Pump Control Circuit (SC300 & SC400)
- Fuel Pump Pressure (All Models)
- Fuel Pressure Regulator (All Models)
- Fuel Control
- Fuel Pump Resistor
- Fuel Cut System Operation
- Fuel Delivery
- Ignition System
- Emission Systems & Sub-Systems
- Variable Valve Timing (VVT) System
- Throttle Controls
- Miscellaneous Controls
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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