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p72 ECU, has blown Q31 transistor.

Discussion in 'ECU's, Electronics, and Tuning' started by prettylewtm, Oct 22, 2007.

  1. prettylewtm

    prettylewtm New Member

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    ok what does this transistor do? i bought the ECU guy said it was chipped. and it is. i opened it up after i bought it. and i also found a blown transistor at q31 on the board. does anyone know what this transistor controls? also cant i just replace it with another one from like radio shack or somethin. let me know please.:D
     
  2. prettylewtm

    prettylewtm New Member

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    nevermind i think i figured it out, its just the purge output signal. well i dont have EVAP anymore so who cares!! lol
     
  3. DJESCO

    DJESCO New Member

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    TEST / TROUBLE SHOOTING HELP GUIDE and REPAIR INFO by DJ Esco
    -----------------------------------------------------------------------------------
    Note: Keep in mind sometimes the problem will re-occur immediately after repair is performed with Q31 or Q34s
    I have dealt with may of these in my days.
    ---------------------------------------------

    The most common are Q34 and Q31
    Q34 controls the secondary runners
    Q31 controls the evap solenoid

    if Q34 is damaged be sure to check R77 by use of the tombstone method. keep in mind that on P28 and simular boards which normally do not control secondary runners these are damaged due to 12VDC being sent to a grounded output. you may want to consider using a relay depending on the vehicle application (year make model)

    if Q31 then you may have a bad IAT sensor (melted) chack wiring purge plug may be connected instead of the intake temp sensor plug (common mistake)

    I have done many repairs of these and even repaired attempted repairs done by other individuals, I dont mind helping anyone with this or other ECU related issues or questions, feel free to contact me anytime if you need.

    DJ Esco
    www.ecumods.com
    (832)798-0000
     
    Last edited: Feb 14, 2010
  4. Riviera

    Riviera New Member

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    alright ive blown the q31 but it seems there no way the sensors can be the wrong way around because the way the loom is taped and conduit is installed it just doesn't allow it. i had a look last night...

    plus my MPG on the P2T ecu has been fine wouldnt it have suffered if they were wrong?


    EK4 JDM B16A running on a P2T, converting to P28 with S200 and a OBDII to OBD1 conversion harness
     
  5. K2e2vin

    K2e2vin Senior Member

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    Most people do install the connector on the wrong sensor; the IAT and the Purge solenoid are close to each other and use the same connector.

    Not really, the ECU can run fine without IAT but would throw a code and probably won't run to it's fullest potential.
     
  6. Riviera

    Riviera New Member

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    ok found out yesterday my sensor in the 4th or 1st runner was melted, but did not look fresh.
    wonderin if anyones got a wiring diagram they could post up for all those connectors in that area..
    what colours go to which sensor.. etc...
     
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