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 Toyota Corolla Base, AutomaticFACTORY OEM SERVICE PROCEDURE
Engine Controls - System/Component Tests
- Introduction
- A/C Switch Description
- Airflow Meter/Sensor Test
- 4WD Air Temp Sensor Test
- Coolant Temp Sensor Test
- EGR Gas Temp Sensor Test
- Neutral/Start Switch Check
- Oxygen (O2) Sensor Feedback Voltage Test
- Sub-Oxygen Sensor Test
- Oxygen (O2) Sensor Heater Test
- Throttle Position Sensor (TPS) Check
- Manifold Absolute Pressure (Map) Sensor - (4WD 4A-FE)
- Vehicle Speed Sensor (VSS) - Analog Type
- Circuit Opening Relay Check
- EFI Main Relay Test
- Fuel Delivery Check
- Fuel Injector Check
- Fuel Pressure-Up System - 2WD (4A-GE)
- Deceleration Fuel-Cut System
- Cold Start Injector Test
- Cold Start Injector Time Switch Test
- Auxiliary Air Valve System Test
- Idle-Up System Test - 4WD (4A-FE)
- Idle-Up System Test - 2WD (4A-GE)
- Ignition System Diagnostic Code Tests
- Spark Test
- Primary Coil Resistance Tests
- Secondary Coil Resistance Tests
- Pick-Up Coil Resistance Test
- Pick-Up Coil Air Gap Check
- Dashpot Control System Test
- Exhaust Gas RECIRCULATION (EGR) Check
- EGR Vacuum Modulator Test
- Bi-Metallic Vacuum Switching Valve (BVSV) (2WD 4A-GE)
- Bi-Metallic Vacuum Switching Valve (BVSV) (4WD 4A-FE)
- Vacuum Switching Valve (VSV) (2WD 4A-GE)
- Fuel Evaporation Tests
- Maintenance
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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