Main Relay Circuits

Toyota utilizes several different EFI Main Relay circuits depending on application. These circuits can be categorized into four distinct types.

1) Dual contact EFI Main Relay, ignition switch controlled

2) Single contact EFI Main Relay, ignition switch controlled

3) Dual EFI Main Relays, ignition switch or ECU controlled

4) Single contact EFI Main Relay, ECU controlled

Generally speaking, the EFI Main Relay supplies current to the following major circuits:

• Injectors (dual relay or dual contact relay only)

• Circuit opening relay (power contact and pull-in windings)

• Air flow meter VB circuit (when so equipped)

• Output Actuator Vacuum Switching Valves (VSV)

- Fuel Pressure Up (FPU)

- Exhaust Gas Recirculation (EGR)

- Throttle Opener

• ISC motor/solenoid windings

• Check connector +B terminal

Because the EFI Main Relay supplies battery voltage to the +B terminal of the check connector when the ignition switch is in the run position, this is an excellent place to perform a quick check of the relay function.

What Efi Main Relay

Dual Contact (Single Relay), Ignition Switch Controlled This EFI Main Relay configuration is used on the Conventional eFi system. It uses separate power contacts to supply current to the fuel injector/ignition circuits and the ECU/circuit opening relay circuit. This limits current flow that the ECU power contact must handle.

This configuration improves the reliability of the relay, reduces possible voltage drop, and also isolates any inductive noise from the injectors to the EFI Computer by utilizing the battery as a large capacitor.

Toyota Camry Efi Main Relay
Do It Yourself Car Diagnosis

Do It Yourself Car Diagnosis

Don't pay hundreds of dollars to find out what is wrong with your car. This book is dedicated to helping the do it yourself home and independent technician understand and use OBD-II technology to diagnose and repair their own vehicles.

Get My Free Ebook


Responses

  • Delmo
    Where is efi main relay on 07 camry?
    3 years ago
  • Temesgen
    WHAT IS TOYOTA ENGINE CONTROL RELAY?
    3 years ago
  • sofia neftalem
    Where the position of ignition main relay for Toyota Land cruiser?
    3 years ago
  • Selamawit
    What is function of main relay?
    2 years ago
  • jana
    How do main relay work toyota?
    2 years ago
  • thomas
    What does the relay fuse do in a 2010 Toyota yaris?
    2 years ago
  • Pancrazio
    Where are the main relays in a toyota sienna 2006?
    2 years ago
  • lavinia
    What does a toyota relay corol?
    2 years ago
  • leila kuparinen
    Which efi switch is main on 96 toyota carolla?
    1 year ago
  • Leah
    What is the functions d4d toyota relays?
    1 year ago
  • rasmus
    What is the function of relay in Toyota corolla?
    1 year ago
  • harris
    What is single electrical circute of toyota?
    1 year ago
  • gaetano
    What are the relays next to the ecm on a 97 Toyota Avalon?
    1 year ago
  • robel
    Why used main relay in diesel engine?
    1 year ago
  • Hagos
    How to test corrola relay switch?
    11 months ago
  • odetta
    What is the purpose of Engine Main Relay in the vehicle?
    11 months ago
  • sebastian
    How to test engine main relay 1998 corolla?
    10 months ago
  • TESFALEM FILMON
    Is there relay and a fuse for the efi system?
    10 months ago
  • kim
    What is a toyota circuit open relay diagram?
    10 months ago
  • DONALD SHAW
    Where is main relay on 2013 toyota siena?
    9 months ago
  • Anne
    How to check the main relay in a 1987 Toyota 1 ton truck?
    9 months ago
  • senay
    What make efi main relay of camry hot?
    9 months ago
  • AZIZ FUTSUM
    What are the functions of relay in toyota camry?
    8 months ago
  • Anne
    What function does a engine main relay do?
    8 months ago
  • ANNE KOEHLER
    What does tazz main engine relay?
    8 months ago
  • carson
    What controls the Circuit opening relay on toyota camrey?
    7 months ago
  • america
    How do a toyota yaris relay work?
    6 months ago
  • boyd
    How to id different relays 2002 toyota celica?
    6 months ago
  • duenna
    How much for the main relay and fuel pump relay for a 1987 Toyota 22 re EFI engine?
    5 months ago
  • constance
    What does camry engine management relay do?
    5 months ago
  • nella
    Where is the efi relay on 2011 rav 4?
    3 months ago
  • alaric
    What doe main engine relay control on 2000 toyota camry v6?
    3 months ago
  • Ciara
    Where is the central relay fuse 2003 toyota tacoma?
    3 months ago
  • robert
    Where is the main engine relay on a 2010 tayota corolla u tube?
    3 months ago
  • gilly twofoot
    Where is the relay switch on a toyota avalon?
    2 months ago
  • Selamawit Yonatan
    What does main engine relay operate on 2000 toyota camry v6?
    2 months ago
  • rosaria
    What does a start relay do in 2000 rav4?
    2 months ago
  • Ferdinando
    How to test fuel relay on 2001 toyota rav4?
    2 months ago
  • Iago
    How to test 1991 toyota corolla relays?
    2 months ago
  • Roxanne
    Where is the circuit opening relay 1993 toyota camry?
    2 months ago
  • fabiana
    Where is circuit opening relay on a trh 201 hiace with a 2.7 ltr engine?
    1 month ago
  • Fethawi
    How many relays does a 2001 toyota rav4 on fuel system?
    1 month ago
  • abelardo
    What does relay switch 9008498032 do in toyota rav4?
    1 month ago
  • Marco
    Where is the ECM fuse on my 91 Toyota pickup truck?
    20 days ago

Post a comment