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Home >> Toyota >> 1991 >> Corolla Base, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Basic Testing - 4-CYL >> Fuel System >> Fuel Pump Control Circuit >> Circuit Opening Relay
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Circuit Opening Relay

  1. Circuit opening relay controls fuel pump circuit. ECU receives an input signal at STA terminal when engine is cranking. This starter signal is also applied to terminal STA of circuit opening relay.
  2. Starter signal energizes circuit opening relay during cranking, which in turn activates fuel pump. On all models except Celica, Corolla (4A-FE) and Tercel, fuel pump switch in airflow meter provides relay ground. On Celica, Corolla (4A-FE) and Tercel, circuit opening relay is grounded by ECU through FC terminal.
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