OEM MK4 management wiring => Mk1/2/3 harness install FAQ (Now with added dieselness!)

Discussion in 'Engines' started by rubjonny, Nov 8, 2013.

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  1. MATTY_NEWELL

    matty_newell Paid Member Paid Member

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    Where does the battery positive go on the fusebox, as my Y3 has a short wire in it, and fusebox diagram said Y3, cheers
     
    matty_newell, Apr 16, 2016
    #261
  2. PHIL_J

    Phil_j New Member

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    Just after a bit of help / clarification..

    I'm in the middle of the swap, fitted both parts of the loom to the car. I've used original relay setup with the 428 relay, but I have 12v to the relay constantly with or without the ignition on, when I put the relay in its triggered even without the ignition. Have I done something wrong with the wiring for the Ecu? Or is it that I'm missing something?

    Do I need to swap the 428 relay for a 109 relay?

    Also the fuel pump isn't priming, I haven't really looked into the 12v or pump issue yet as I ran out of time to look into it.
     
    Phil_j, Apr 17, 2016
    #262
  3. rubjonny

    rubjonny Administrator Staff Member Admin

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    matty: Y/3 or Y/4 is fine for the battery live, all the Ys are on a common bus (1 & 2 are too small for the battery cable tho) the short wire you mention sounds like the loop for 30b, sometimes this goes to the Y but usually its looped to the 30 terminal next to it. either way is fine, you could even put the battery live to the 30 terminal and leave the 30b looped to Y/3 or 4 and it would work just as well :thumbup:

    phil: you should have a permanent live to terminal 30 & 86 on the relay, this is the thick white/red feed. The ECU earth the purple wire on relay pin 85 when it sees an ignition live to pin 3, which originally was fed by the T6 plug pin 1. Once the relay is triggered by the ecu you should then see 12v on pin 87 to power up the coilpacks and the ecu main power feed

    Relay pin 87 should only be triggered when your ecu is powered up,
     
    rubjonny, Apr 18, 2016
    #263
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  4. PHIL_J

    Phil_j New Member

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    Cheers John! I get where I went wrong now you say that, on the other issue with the fuel pump. I don't remember refitting the red jumper cable on the fuse of when I reconnected stuff. Could this be why the fuel pump isn't priming? Thanks again!
     
    Phil_j, Apr 18, 2016
    #264
  5. rubjonny

    rubjonny Administrator Staff Member Admin

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    if the 30-30b jumper is missing that'll be why, as the 30b terminal is the live input for the fuel pump relay :)
     
    rubjonny, Apr 18, 2016
    #265
  6. PHIL_J

    Phil_j New Member

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    That sorts that out then!
    At least the issues were easily sorted..
     
    Phil_j, Apr 18, 2016
    #266
  7. PHIL_J

    Phil_j New Member

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    Sorry to keep on at this, got the pump issue sorted - just then jumper cable as said above.

    I've checked the wiring for the Ecu / cool relay, I have an ignition live to pin 3. The old coil wire, g1/4 and get 12v to the Ecu when switching on the ignition. But the relay stays on with the keys out and I have to remove the battery to stop it from having 12v. But once the battery is reconnected it's at 0v until the ignition is switched on again. Any ideas? I'm guessing the relay should go back to 0v as soon as the ignition is turned off?
     
    Phil_j, Apr 20, 2016
    #267
  8. rubjonny

    rubjonny Administrator Staff Member Admin

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    the ecu/coil relay is switched by an earth from the ecu pin 21 to pin 85 on the relay, so check that pin is only earthed when the ignition is on. if its still earthed ignition off then you have a fault in the loom or the ecu somewhere.

    have you checked pin 3 on the ecu while the issue is occurring, i.e. probe it with the ecu plugged in and ecu/coil relay stuck on?
     
    rubjonny, Apr 22, 2016
    #268
  9. PHIL_J

    Phil_j New Member

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    Yeah, pin 3 looses the 12v feed when the ignition is switched on and off. Need to have a look through the wiring tonight when I go to the garage.
     
    Phil_j, Apr 22, 2016
    #269
  10. MATTY_NEWELL

    matty_newell Paid Member Paid Member

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    coulple more questions, how do you wire the starter motor up ?...... where does the long cable off the alternator go to,......i have a cable comiong off bat - that is quite thick where does that go, should of took pictures when took engine out,

    i also tried the link for your wiring diagrams a couple times @rubjonny and link does not seem to work for me,

    cheers
     
    matty_newell, May 4, 2016
    #270
  11. rubjonny

    rubjonny Administrator Staff Member Admin

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    with the starter you just keep the original wire in the engine loom from your car, you may want to splice or crimp a mk3/4 plug on it if its a mk1/2 as the mk3/4 use a nice clippy plug for it. you may find the mk4 wire will reach even, lay it out and see. the fusebox side pin is the same as 90sepc CE2 fusebox so could be swapped. if not you could strip one out of a mk3 loom for example if you didnt have a prop tool to crimp new pins and dont want to splice this wire.

    the battery live goes straight to the 13mm nut stud on the starter motor. With the thick wire on the alternator this goes to the starter stud on a mk2/3, on a mk4 it goes to the battery box so is a little long when put on the starter. if you add a mk4 battery bnox to your car though it'll go right to it as per factory mk4 :)

    with my link you need to be logged into google or gmail, plus it wont work on apple devices for some reason!
     
    rubjonny, May 5, 2016
    #271
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  12. MATTY_NEWELL

    matty_newell Paid Member Paid Member

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    thats helped sort some things, where does the thick battery negative go, its earthed to chassis and there is one wire left where does this go,
    batt neg.jpg
     
    matty_newell, May 5, 2016
    #272
  13. rubjonny

    rubjonny Administrator Staff Member Admin

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    the long end goes to the engine, look at the 2 upper bolts that hold the box to the engine there should be a stud on the end of one of those :)
     
    rubjonny, May 6, 2016
    #273
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  14. MATTY_NEWELL

    matty_newell Paid Member Paid Member

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    Thanks again rubjonny, another thing can I wire the Mk4 Orange pin 6 to W1 without the speed converter thingy if using Mk3 clocks in Mk2

    Cheers
     
    matty_newell, May 8, 2016
    #274
  15. rep

    rep Forum Member

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    @ Matty. Yes, this is what i done on my conversion as i had an ABF engine in before swapping. There was already a blue single felmale plug in the ABF loom. I just cut that and connected Orange Pin6 to W1 with this. Works fine with Mk3 clocks.

    Good luck
     
    rep, May 8, 2016
    #275
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  16. rubjonny

    rubjonny Administrator Staff Member Admin

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    you dont need any kind of converter for the VSS wire, even with mk1 or mk2 clocks. the MFA speedo sender fitted to the GTI/cruise/aktiv equipped cars sends the correct pulse for the MK4 ECU :)
     
    rubjonny, May 9, 2016
    #276
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  17. MATTY_NEWELL

    matty_newell Paid Member Paid Member

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    Thank you both for replies, will get that one sorted now,

    And where can you buy a new obd2 port, or replacement pins, cheers
     
    matty_newell, May 9, 2016
    #277
  18. rubjonny

    rubjonny Administrator Staff Member Admin

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    the mk3 ports use micro timer pins which are easy to get. the mk4 ports not sure on what they are?
     
    rubjonny, May 12, 2016
    #278
  19. BITZ N PIECES

    Bitz n pieces New Member

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    Grrrr blinking cars lol

    I've tried to follow this as good as I can ( I must useless) but then I'm not using this on a VW vehicle

    What doesn't help is I'm not even sure I'm using the forum properly or not :( ..... I did say I'm useless

    John did I send you a message ???
     
    Bitz n pieces, May 17, 2016
    #279
  20. BITZ N PIECES

    Bitz n pieces New Member

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    John just seen your reply and oops sorry

    Also oops to late I had already cut it ....... I've also worked out what dbw stood for ...... See said I was useless
     
    Bitz n pieces, May 17, 2016
    #280
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