OEM management wiring: 1.8T => Mk2 harness install FAQ

Discussion in '1.8 & 1.8T' started by 20v_jimmy, Dec 29, 2009.

  1. rubjonny

    rubjonny Administrator Staff Member Admin

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    ok one thing, when you converted to wideband did you add a power pin from ecu/coil relay to ecu pin 121, as the original APU loom doesn't have this
     
  2. jim poter New Member

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    I origrinally did not but now have after reading back through previous advice you have given to others.
    I am today going to check the locations on the loom connector to ecu today to enusre the new pins are in the correct location.
    I remember the two lamba pins i added were offset by 1 pin to each other at the ecu plug.
    i beleive this is wrong as doing a recount they should directly in line with each other.

    thanks for the help very much valued.
     
  3. jim poter New Member

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    checked the ecu plug wiring and have found a pin error, will rectify and see what happens.

    thx.
     
  4. jim poter New Member

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    ok so , so there is a pin in ecu plug for 121, only other extra pins added were for lambda and they were 71 and 52.
    all these have been checked and confirmed as in the correct locaiton.


    I have 3 fault codes.

    18056 powertrain dta bus - P1648 35 -00 failure

    17987 - Throttle actuator (j338) - P1579 - 35 -00 Adaption not started

    17069 - ECM power relay - P0685 - 35 - 00 open circuit.

    ECM power relay is wired as such..

    Pin 30 - perm 12v
    Pin 87 - to pin 121 of ecu
    Pin 85 - black/white to pin 21 of ecu
    Pin 86 - ign live
    my understanding is that this would or should remove the 17069 code.

    17987 becuase its not seing a voltage from somewhere ? or the body is Dead ?

    18056 - i dont run the clocks etc. which is what i believe that relates to .

    i've ordered a throttle body on the off chance the 1 i have is dead.
    i have a spare wideband ecu which i can swpa out to eliminate ECU issue, if as i believe the wiring is now correct.
     
  5. rubjonny

    rubjonny Administrator Staff Member Admin

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    17069 can mean you've lost the permanent live feed to the ECU pin 62, reason being in the factory harness this pin is fed from the same source which powers the ECU relay pin 30
     
  6. jim poter New Member

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    thankyou i will check this today.
     
  7. jim poter New Member

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    ok, so i have power at pin 62.

    however

    ecu relay which is wired -

    Pin 30 - perm 12v
    Pin 87 - to pin 121 of ecu
    Pin 85 - to pin 21 of ecu
    Pin 86 - ign live

    shows the following voltages with igniton on.

    pin 85 12v
    pin 30 12v
    pin 86 12v
    pin 87 0

    ive now added a earth to pin 21 and it runs and throttle is back.

    seems i was a fault the whole time.

    edited to remove mistake
     
    Last edited: Mar 15, 2022
  8. rubjonny

    rubjonny Administrator Staff Member Admin

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    earth to 121?
     
  9. jim poter New Member

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    yes, the only was i can get it ro run is, provide a earth to pin 21 on the relay.
    this then powers up everything.

    it still show a relay error , but runs and drives.
     
  10. rubjonny

    rubjonny Administrator Staff Member Admin

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    pin 21, that makes more sense. 121 is the power from relay to ecu ;)

    soooo. whats the part number of your ecu? some of them dont use ecu relay which would explain why its not triggering it, but then it shouldnt show a fault code for it.... otherwise you have a wire fault between ecu pin 21 and the relay pin 85 or a bad ecu
     
  11. jim poter New Member

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    its a 8n0 906 018 aq from a ARY running a AUQ file crossflashed.
    i have a spare ECU, which is the same as above so can swap it out to prove the fault at either point.

    howver currently it runs and drives, so im hald tempted not to do anything just yet.
     
  12. rubjonny

    rubjonny Administrator Staff Member Admin

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    yeah that should have relay functionality, so that leaves wire fault or bad ecu. it doesnt really matter I dont think though
     
  13. jim poter New Member

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    no agreed, as it works i will leave it until such a time as i can do without my van for a few days. (pic below)

    thankyou for your help. bus.jpg
     
  14. jim poter New Member

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    @rubjonny do you think you can use a mk5 accelerator pedal ? pedal in the van is from stock the same in design, hinged at the floor.
    current setup is damm painful and will need bulkhead modding to get it to sit correct.
    i can see the connector is different , but still 6 pins.
    however internals appear differnet also. has anyone done this with success.
    google returns nothing of help.
     
  15. rubjonny

    rubjonny Administrator Staff Member Admin

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    most say no, different. some say you can edit pedal map in ecu to suit, though that was mk5 r32 to suit mk4 pedal. but yeah, standard it wont work
     

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