Circuit Opening Relay
- Circuit opening relay controls fuel pump circuit. ECU receives an input signal at "STA" terminal when engine is cranking. This same starter signal is also applied to terminal "STA" of circuit opening relay.
- Starter signal energizes circuit opening relay during cranking, which in turn activates the fuel pump. On all except Supra (7M-GTE), when airflow meter senses airflow to engine, fuel pump switch in airflow meter provides the relay ground. On Supra (7M-GTE), circuit opening relay is grounded by ECU through "FC" terminal.
Fuel Pump Relay & Fuel Pump Resistor (Cressida & Supra)
On these models a separate fuel pump relay and resistor are used between the circuit opening relay and the fuel pump.
NOTE:
For more information on testing relays and fuel system components, see I - EFI SYS/COMP TESTS article.