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"CHECK ENGINE" light test

Discussion in 'Gen 2 Prius Main Forum' started by tortus, Jun 8, 2010.

  1. tortus

    tortus New Member

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    I have driven my 2009 prius 17000 miles in 14 months with no issues that have triggered "check eng" light (MIL). To test the functionality of that part of the engine management computer that monitors for faults, I removed the fuel filler cap and drove 118 miles with several stops and restarts with no MIL. My two previous cars, 1999 chev metro and 2007 nissan versa, would show a MIL with this test. When ignition on but before "ready" light, all of the warning lights are on including the MIL. Can anyone think of another test that I can do to satisfy myself on this matter or should I not persue this issue. >>>>Tortus
     
    #1 tortus, Jun 8, 2010
  2. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Here's a test you can easily perform: disconnect a wiring harness connector that connects to a spark plug igniter. The engine should run very rough on 3 cylinders, and that should prompt the check engine light to come on.
     
    #2 Patrick Wong, Jun 9, 2010
  3. hobbit

    hobbit Senior Member

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    OBD-II systems are required to have a power mode that does a
    "lamp test" of various things, notably including the MIL, to make
    sure the *lamp* is working before any emissions tests are done.
    In the Prius, that mode is IG-ON that you get by *not* pressing
    the brake and toggling the power button two times to get all
    the dash lights to go on. Upon pressing the brake and hitting
    the button again it should go to READY [equivalent of starting
    the engine in conventional cars] and the MIL should go out,
    unless there's a problem.
    .
    Almost exactly equivalent to standard inspection procedure.
    .
    If you want to actually force an error, there are numerous ways
    to do it. Another really easy one is to disconnect the mass-airflow
    connector on the front of the air-box; the ECM should signal
    an immediate problem.
    .
    _H*
     
    #3 hobbit, Jun 9, 2010
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