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
EFI Main Relay
- The EFI fuse supplies constant battery voltage to the EFI main relay. EFI main relay supplies battery voltage to +B pin of engine check connector. If fuel pump will not turn on when +B and FP pins are jumpered, with ignition on, check EFI main relay. See Figure and Figure.
- Also, check circuit that turns on EFI main relay. Depending on model, relay may either be turned on directly by ignition switch or by M-REL terminal of ECU. For more information on wiring, see the WIRING DIAGRAMS article in this section.
- On all models, EFI main relay provides battery voltage to +B terminal of circuit opening relay.
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.