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 MANUALSTOYOTA1992CAB & CHASSIS STANDARD, R150REPAIR AND DIAGNOSISENGINE PERFORMANCESYSTEMENGINE CONTROLS - BASIC TESTING - V6FUEL SYSTEMFUEL PUMP CONTROL CIRCUITCIRCUIT OPENING RELAY
1992 Toyota Cab & Chassis Standard, R150
Circuit Opening Relay
1992 Toyota Cab & Chassis Standard, R150SECTION Circuit Opening Relay
- Circuit opening relay controls fuel pump circuit. The Electronic Control Unit (ECU) receives an input signal at STA terminal when engine is cranking. Starter signal is also applied to terminal STA of circuit opening relay.
- Starter signal energizes circuit opening relay during cranking. The circuit opening relay then provides voltage to the fuel pump.
- Fuel pump switch in airflow meter provides the ground for circuit opening relay. On all other models, circuit opening relay is grounded by the ECU through the FC terminal.
NOTE:
For more information on testing relays and fuel system components, see SYSTEM & COMPONENT TESTING article.
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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.