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.
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HOMESERVICE MANUALSTOYOTA2004CELICA GT, STANDARDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 28 (ENGINE CONTROLS - THEORY & OPERATION)
2004 Toyota Celica GT, Standard
Section 28 (Engine Controls - Theory & Operation)
2004 Toyota Celica GT, StandardSECTION Section 28 (Engine Controls - Theory & Operation)
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2002 Lexus SC 430, 2002 Lexus RX 300, 2002 Lexus LX 470, 2002 Lexus LS 430, and 2002 Lexus IS 300. However, it is still accessible from the selected car via links, so may be relevant.
- Introduction
- Air Induction System
- Computerized Engine Controls
- Engine Control Module (ECM)
- Engine Immobilizer System
- Variable Valve Timing (VVT) System
- Input Devices
- Notes
- Accelerator Pedal Position Sensor (GS300, GS430, IS300, LS430, LX470 & SC430)
- Air/Fuel (A/F) Ratio Sensor (ES300 & RX300)
- A/C Switch
- Battery Signal
- Brakelight Signal
- Camshaft Position Sensor
- Crankshaft Sensor
- Engine Coolant Temperature (ECT) Sensor
- Heated Oxygen Sensor (HO2S)
- Intake Air Temperature (IAT) Sensor
- Knock Sensor
- Ignitor (GS300 & IS300)
- Mass Airflow (MAF) Sensor
- Park/Neutral Position (PNP) Switch
- Throttle Position (TP) Sensor
- Vapor Pressure Sensor (RX300)
- Vapor Pressure Sensor (Except RX300)
- Variable Valve Timing Sensor (ES300, GS430, LS430, RX300 & SC430)
- Vehicle Speed Sensor (At Transmission/Transaxle)
- Vehicle Speed Sensor (With Wheel Speed Sensors)
- Output Signals
- Notes
- ACIS Vacuum Switching Valve (VSV)
- A/F Heater Relay
- Circuit Opening Relay
- EFI Main Relay
- Electronically Controlled Transmission/Transaxle
- Electronic Spark Advance System
- EVAP Canister Vacuum Switching Valve
- Fuel Injectors
- Fuel Pump
- Fuel Pump Electronic Control Unit
- Idle Speed Control System
- Intake Air Control Valve
- Malfunction Indicator Light
- Self-Diagnostics
- Throttle Control Motor
- Fuel System
- Fuel Delivery
- Air/Fuel (A/F) Heater Relay (ES300 & RX300)
- Circuit Opening Relay (ES300 & RX300)
- Circuit Opening Relay (LS430 & SC430)
- EFI Main Relay (ES300 & RX300)
- EFI Main Relay (GS300, GS430 & IS300)
- EFI Main Relay (LS430 & SC430)
- EFI Main Relay (LX470)
- Fuel Pump (ES300, IS300, LS430, RX300 & SC430)
- Fuel Pump & Fuel Pump Electronic Control Unit (GS300 & GS430)
- Fuel Pump, Fuel Pump Electronic Control Unit & Fuel Pump Switch (LX470)
- Fuel Pressure Regulator (LX470)
- Fuel Pressure Regulator (Except LX470)
- Fuel Pressure Pulsation Damper
- Fuel Control
- Idle Speed
- Fuel Delivery
- Ignition System
- Emission Systems
- Self-Diagnostic System
- Miscellaneous Controls
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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.