ECU Grounds and Quick Checks

No electrical circuit will function normally without a dependable ground. Toyota EFI systems use a redundant ground system which significantly reduces the chance of ground problems; however, this circuit should never be overlooked when troubleshooting ECU related systems.

The E2 circuit serves as a signal return or sensor ground. Referring to an EWD, you will notice that the throttle position sensor, water and air temperature sensors, and air flow meter all flow current to ground through circuit E2. The ECU supplies a chassis ground through the E1 circuit which typically terminates somewhere on the engine.

Circuits E01 and E02 serve as grounds for the fuel injector driver circuits. To provide a redundant ground for the ECU, these two grounds are tied to the E1 circuit through a diode. In the event that the E1 wiring to chassis is open circuit, E1 circuit current could flow through the diode to ground. The diode serves to prevent voltage spikes from the injectors from interfering with other ECU circuits.

It is not uncommon for many or even all ECU grounds to terminate at the same point and fasten to the engine with the same fastener. Sometimes a ground fault is due to one fastener being left loose after a service procedure has been performed.

It is a fairly simple task to confirm the integrity of all ECU ground circuits in fairly short order. Two methods can be used to identify and isolate a ground fault; these are the circuit continuity check and the voltage drop check. These procedures along with checks of the power distribution circuits are addressed in exercises 5-1 and 5-2.

Fuel Injection Control

Drawing Corolla 4efe E11

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Responses

  • Lawrence
    How to check ecu ground diode and grounds exercise?
    4 years ago
  • ruta
    Where is the 2010 toyota rav4 ecu ground cable?
    3 years ago
  • regina
    What is Ecu ground circuit?
    3 years ago
  • eustorgio
    How to check ecu for 2000 Toyota camry?
    3 years ago
  • jukka
    How to test ground cable in ECU of car?
    3 years ago
  • pat
    How to test ecu grounds?
    2 years ago
  • Lauri
    Where are all the ground wires located on the 1996 toyota corolla?
    2 years ago
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    2 years ago
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    How to test a circuit ecu rav4 2003?
    2 years ago
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    How to test for ground toyota 4afe corolla?
    2 years ago
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    How many ground wires are in 1989 toyota camry.?
    2 years ago
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    How to test ecm on 2000 celica?
    2 years ago
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    How test ground on ecm on 2000 celica?
    2 years ago
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    How to locate toyota corrolla 2005 chasis ground wire?
    2 years ago
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    What are the functions of ecu in Toyota 2000 model rav 4?
    2 years ago
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    2 years ago
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    HOW TO TEST TOYOTA FUEL CONTROL ECU?
    1 year ago
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    1 year ago
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    Where is ecm ground on 2001 toyota avalon?
    1 year ago
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    How to repair circuits in ecu toyota avalon?
    12 months ago
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    What pins to jump fuel pump power on 2008 toyota camry?
    11 months ago
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    11 months ago
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    What systems dose the ecu control toyota corolla?
    10 months ago
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    Where is the location of my pcm on my 2008 toyota avalon?
    7 months ago
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    6 months ago
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    6 months ago
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    4 months ago
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    3 months ago
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    2 months ago
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    How to check to ground from ecm to wire?
    2 months ago

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