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Fuel Delivery: Notes

Vehicles are equipped with different combinations of fuel system electrical components. For complete wiring circuit of electrical components on a specific model, see appropriate wiring diagram in WIRING DIAGRAMS article.

  1. A/F Heater Relay (Avalon Calif. Emission Vehicles, Camry 3.0L V6 Calif. Emission Vehicles With A/T, Camry Solara 3.0L V6 Calif. Emission Vehicles With A/T & Sienna Calif. Emission Vehicles)

    A/F heater relay may also be referred to as A/F HTR relay. Constant battery voltage is supplied from battery, through A/F heater fuse to one side of A/F heater relay. When A/F heater relay is energized by MREL terminal of Engine Control Module (ECM), A/F heater relay provides battery voltage to +B terminal at A/F sensor. For A/F heater relay location, see A/F HEATER RELAY LOCATION  table.
    A/F HEATER RELAY LOCATION

    Application Location
    Avalon, Camry & Camry Solara In Small Fuse Relay Box At Driver's Side Front Corner Of Engine Comparment, In Front Of Battery
    Sienna (1)
    (1) Located near ECM behind passenger's side of instrument panel and contains a 4-pin connector. See Fig 1.
    Fig 1: Locating A/F Heater Relay (Sienna - Calif. Emission Vehicles)
    G99G08297Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    NOTE: Circuit opening relay is used on all models except Land Cruiser. Circuit opening relay may be identified by appropriate illustration in appropriate SYSTEM & COMPONENT TESTING article.

  1. Circuit Opening Relay (Avalon, Camry & Camry Solara)
    Circuit opening relay controls fuel pump circuit. When EFI main relay is energized, EFI main relay provides battery voltage to one side of circuit opening relay. When ignition is turned on, voltage is supplied through IGN fuse to other side of circuit opening relay. When proper input signals are delivered to Engine Control Module (ECM), circuit opening relay ground circuit is grounded at ECM terminal FC. Circuit opening relay then provides voltage to fuel pump for fuel pump operation. For circuit opening relay location, see CIRCUIT OPENING RELAY LOCATION  table.

  2. Circuit Opening Relay (Celica)

    Circuit opening relay controls fuel pump circuit. When EFI main relay is energized, EFI main relay provides battery voltage to one side of circuit opening relay. When engine is cranking, circuit opening relay receives a start signal which energizes circuit opening relay. Circuit opening relay then provides voltage to fuel pump for fuel pump operation. When start signal is released from circuit opening relay, Engine Control Module (ECM) then controls ground circuit for circuit opening relay at ECM terminal FC. Circuit opening relay then provides voltage to fuel pump for fuel pump operation. For circuit opening relay location, see CIRCUIT OPENING RELAY LOCATION  table.

  3. Circuit Opening Relay (Corolla)

    Circuit opening relay controls fuel pump circuit. When EFI main relay is energized, EFI main relay provides battery voltage to both sides of circuit opening relay. EFI main relay may also be referred to as EFI relay or F-HTR relay. When proper input signals are delivered to Engine Control Module (ECM), circuit opening relay ground circuit is grounded at ECM terminal FC. Circuit opening relay then provides voltage to fuel pump for fuel pump operation. For circuit opening relay location, see CIRCUIT OPENING RELAY LOCATION  table.

  4. Circuit Opening Relay (RAV4)

    Circuit opening relay controls fuel pump circuit. When EFI main relay is energized, EFI main relay provides battery voltage to one side of circuit opening relay. When ignition is turned on, voltage is supplied to other side of circuit opening relay. When proper input signals are delivered to Engine Control Module (ECM), circuit opening relay ground circuit is grounded at ECM terminal FC. Circuit opening relay then provides voltage to fuel pump for fuel pump operation. For circuit opening relay location, see CIRCUIT OPENING RELAY LOCATION  table.

  5. Circuit Opening Relay (Sienna)

    Circuit opening relay controls fuel pump circuit. When EFI main relay is energized, EFI main relay provides battery voltage to one side of circuit opening relay. When ignition is turned on, voltage is supplied through IGN fuse to other side of circuit opening relay. When proper input signals are delivered to Engine Control Module (ECM), circuit opening relay ground circuit is grounded at ECM terminal FC. Circuit opening relay then provides voltage to fuel pump for fuel pump operation. For circuit opening relay location, see CIRCUIT OPENING RELAY LOCATION  table.

  6. Circuit Opening Relay (Tacoma)

    Circuit opening relay controls fuel pump circuit. When EFI main relay is energized, EFI main relay provides battery voltage to one side of circuit opening relay. When engine is cranking, circuit opening relay receives a start signal which energizes circuit opening relay. Circuit opening relay then provides voltage to fuel pump for fuel pump operation. When start signal is released from circuit opening relay, Engine Control Module (ECM) then controls the ground circuit for circuit opening relay at ECM terminal FC. Circuit opening relay then provides voltage to fuel pump for fuel pump operation. For circuit opening relay location, see CIRCUIT OPENING RELAY LOCATION  table.

  7. Circuit Opening Relay (4Runner)

    Circuit opening relay controls fuel pump circuit. When EFI main relay is energized, EFI main relay provides battery voltage to both sides of circuit opening relay. When proper input signals are delivered to Engine Control Module (ECM), circuit opening relay ground circuit is grounded at ECM terminal FC. Circuit opening relay then provides voltage to fuel pump for fuel pump operation. For circuit opening relay location, see CIRCUIT OPENING RELAY LOCATION  table.
CIRCUIT OPENING RELAY LOCATION (1)

Application Location
Avalon Top Corner Of Relay Box Behind Passenger's Side Kick Panel
Camry & Camry Solara In Relay Box At Driver's Side Front Corner Of Engine Compartment, Near Battery & Air Cleaner
Celica (2)
Corolla Center Relay In Relay Box, Behind Driver's Side Kick Panel
RAV4 Top Rear Relay In Relay Box Below Driver's Side Of Instrument Panel, Behind Kick Panel
Sienna In Relay Box At Driver's Side Front Corner Of Engine Compartment Near Battery & Air Cleaner
Tacoma Behind Lower Instrument Panel Cover, Next To Driver's Side Of Steering Column
4Runner Below Right Corner Of Fuse/Relay Box, Behind Lower Instrument Panel Cover At Driver's Side Of Instrument Panel To Left Of Steering Column, Just Above Hood Release Lever
(1) Circuit opening relay may be marked as CIR OPN relay.
(2) Below passenger's side of instrument panel, underneath carpet, near center console, attached to rear of ECM. See Figure.

  1. EFI Main Relay (Avalon, Camry 3.0L V6 & Camry Solara 3.0L V6)

    EFI main relay may also be referred to as EFI relay. EFI fuse supplies constant battery voltage to one side of EFI main relay. EFI main relay is energized by MREL terminal of Engine Control Module (ECM). When EFI main relay is energized, EFI main relay provides battery voltage to circuit opening relay, data link connector No. 1 and various other electrical components. EFI main relay also provides battery voltage to +B terminal of ECM. For EFI main relay location, see EFI MAIN RELAY LOCATION  table.

  2. EFI Main Relay (Camry 2.2L 4-Cyl. & Camry Solara 2.2L 4-Cyl.)

    EFI main relay may also be referred to as EFI relay. EFI fuse supplies constant battery voltage to one side of EFI main relay. EFI main relay is energized when ignition is turned on by voltage supplied through IGN fuse to EFI main relay on vehicles not equipped with engine immobilizer system, or by MREL terminal of Engine Control Module (ECM) on vehicles equipped with engine immobilizer system. When EFI main relay is energized, EFI main relay provides battery voltage to circuit opening relay, data link connector No. 1 and various other electrical components. EFI main relay also provides battery voltage to +B terminal of ECM. For EFI main relay location, see EFI MAIN RELAY LOCATION  table.

  3. EFI Main Relay (Celica)

    EFI main relay may also be referred to as EFI relay. EFI fuse supplies constant battery voltage to one side of EFI main relay. When ignition is turned on, voltage is supplied through IGN fuse to other side of EFI main relay. EFI main relay is then energized and provides battery voltage to circuit opening relay, data link connector No. 1 and various other electrical components. EFI main relay also provides battery voltage to +B terminal of Engine Control Module (ECM) when ignition is turned on. For EFI main relay location, see EFI MAIN RELAY LOCATION  table.

  4. EFI Main Relay (Corolla)

    EFI main relay may also be referred to as EFI relay or F-HTR relay. EFI fuse supplies constant battery voltage to one side of EFI main relay. EFI fuse may also be referred to as F-HTR fuse. When ignition is turned on, voltage is supplied through IGN fuse to other side of EFI main relay. EFI main relay is then energized and provides battery voltage to circuit opening relay, data link connector No. 1 and various other electrical components. EFI main relay also provides battery voltage to +B terminal of Engine Control Module (ECM) when ignition is turned on. For EFI main relay location, see EFI MAIN RELAY LOCATION  table.

  5. EFI Main Relay (Land Cruiser)

    EFI main relay may also be referred to as EFI relay or ECD relay. EFI fuse supplies constant battery voltage to one side of EFI main relay. EFI fuse may also be referred to as ECD fuse. When EFI main relay is energized by MREL terminal of Engine Control Module (ECM), EFI main relay provides battery voltage to +B terminal of fuel pump Electronic Control Unit (ECU) and various other electrical components. EFI main relay also provides battery voltage to +B and +B1 terminals of ECM. For operation of fuel pump ECU and fuel pump switch, see FUEL PUMP ELECTRONIC CONTROL UNIT (ECU) & FUEL PUMP SWITCH . For EFI main relay location, see EFI MAIN RELAY LOCATION  table.

  6. EFI Main Relay (RAV4)

    EFI main relay may also be referred to as EFI relay. EFI fuse supplies constant battery voltage to one side of EFI main relay. When ignition is turned on, voltage is supplied to other side of EFI main relay from the ignition switch. EFI main relay is then energized and provides battery voltage to circuit opening relay, data link connector No. 1 and various other electrical components. EFI main relay also provides battery voltage to +B terminal of Engine Control Module (ECM) when ignition is turned on. For EFI main relay location, see EFI MAIN RELAY LOCATION  table.

  7. EFI Main Relay (Sienna)

    EFI main relay may also be referred to as EFI relay. EFI fuse supplies constant battery voltage to one side of EFI main relay. EFI main relay is energized by MREL terminal of Engine Control Module (ECM). When EFI main relay is energized, EFI main relay provides battery voltage to circuit opening relay, data link connector No. 1 and various other electrical components. EFI main relay also provides battery voltage to +B terminal of ECM. For EFI main relay location, see EFI MAIN RELAY LOCATION  table.

  8. EFI Main Relay (Tacoma)

    EFI main relay may also be referred to as EFI relay. EFI fuse supplies constant battery voltage to one side of EFI main relay. When ignition is turned on, voltage is supplied through IGN fuse to other side of EFI main relay. EFI main relay is then energized and provides battery voltage to circuit opening relay, data link connector No. 1 and various other electrical components. EFI main relay also provides battery voltage to +B terminal of Engine Control Module (ECM) when ignition is turned on. For EFI main relay location, see EFI MAIN RELAY LOCATION  table.

  9. EFI Main Relay (4Runner 2.7L 4-Cyl.)

    EFI main relay may also be referred to as EFI relay. EFI fuse supplies constant battery voltage to one side of EFI main relay. When ignition is turned on, voltage is supplied through IGN fuse to other side of EFI main relay. EFI main relay is then energized and provides battery voltage to circuit opening relay, data link connector No. 1 and various other electrical components. EFI main relay also provides battery voltage to +B terminal of ECM. For EFI main relay location, see EFI MAIN RELAY LOCATION  table.

  10. EFI Main Relay (4Runner 3.4L V6)

    EFI main relay may also be referred to as EFI relay. EFI fuse supplies constant battery voltage to one side of EFI main relay. EFI main relay is energized by MREL terminal of Engine Control Module (ECM). When EFI main relay is energized, EFI main relay provides battery voltage to circuit opening relay, data link connector No. 1 and various other electrical components. EFI main relay also provides battery voltage to +B terminal of ECM. For EFI main relay location, see EFI MAIN RELAY LOCATION  table.
EFI MAIN RELAY LOCATION

Application Location
Avalon, Camry, Camry Solara & Celica In Fuse/Relay Box At Driver's Side Front Corner Of Engine Compartment, Near Battery
Corolla In Fuse/Relay Box At Driver's Side Front Corner Of Engine Compartment, Near Strut Tower
Land Cruiser In Fuse/Relay Box At Driver's Side Front Corner Of Engine Compartment, Near Battery
RAV4 In Fuse/Relay Box Behind Driver's Side Of Instrument Panel, Next To Steering Column, Or In Fuse/Relay Box At Driver's Side Front Corner Of Engine Compartment, Near Strut Tower
Sienna, Tacoma & 4Runner In Fuse/Relay Box At Driver's Side Front Corner Of Engine Compartment, Near Battery
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