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Haldex controller question

Discussion in 'A3/S3 Forum (8L Chassis)' started by jojo, Nov 19, 2013.

  1. jojo
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    jojo S3 Drift King! Staff Member Moderator

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    [Nov 19, 2013]
    Not your usual question, but would it be ok to just plug my Haldex performance controller under the car without bolting it up? No oil running through it, just want to eliminate the no comms DTC from VCDS. Shouldn't't be a problem right? The part is kind of expensive to break, so want to make sure!
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  3. hoffmanvp3
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    hoffmanvp3 Active Member

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    [Nov 19, 2013]
    Did u check the earth strap for the controller that's still bolted on?
    I don't see why the pre charge pump won't come on if your not requesting it to operate via VCDS but sure one will correct me if I'm wrong:)
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  4. jojo
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    jojo S3 Drift King! Staff Member Moderator

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    [Nov 19, 2013]
    My car doesn't have an earth strap as far as I know? VCDS is just showing no comms to controller, so I wanted to plug my unfitted performance one on to test the comms. Will the lack of oil effect it's operation, it's just a stepper motor that opens and close a valve right?
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  5. hoffmanvp3
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    hoffmanvp3 Active Member

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    [Nov 19, 2013]
    Not really sure tbh but there should be an earth strap iirc as that'll prob be causing ur no coms
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  6. Gops
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    Gops 6th gear @7000rpm

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    [Nov 19, 2013]
    It should work.. But be warned not to turn over the car.. It'll piss out oil! I'm not sure if the pre charge pump activates on ignition and oil may come out! It's not a hard job popping it back out anyhow. You using MY blue haldex? :cool:
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  7. jojo
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    jojo S3 Drift King! Staff Member Moderator

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    [Nov 19, 2013]
    I'm keeping my original Haldex in situ, just want to plug the performance one into the lead to confirm it's the lead that's faulty.

    It did come off your car, but it Miiiiine! :moa:
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  8. Big Al
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    Big Al A4 sold, a Lupo for now!

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    [Nov 20, 2013]
    Hi Joe

    The Haldex controller may work if just plugged in, but without an earth it may malfunction and damage the circuitry. Apparently many of the controllers fail in this way, as earth straps often break. Your diff unit should have an earth strap and they are easy enough to make. There should be screw posts on both the shell and trans. See this picture of my Haldex unit which I'm selling.

    Al

    [​IMG]
    [​IMG]
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  9. Gops
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    Gops 6th gear @7000rpm

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    [Nov 20, 2013]
    Pre facelifts didn't have an earth strap
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  10. Big Al
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    Big Al A4 sold, a Lupo for now!

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    [Nov 21, 2013]
    Really? That's weird. Maybe the loom wiring on pre-facelifts is different too, including an earth in the wiring? I can't see how the controller would operate reliably without the earth/-ve ground strap.
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  11. rupe
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    rupe A3 TQS

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    [Nov 21, 2013]
    my facelift doesn't have a ground strap either and theirs no evidence of their ever having been one, I can see the stud on the floor pan where it would go, but it's covered in the factory underbody stuff.
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  12. Matt78
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    Matt78 Member

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    [Nov 21, 2013]
    I'm having my Y plate S3 looked at tomorrow because of this same no comms code....
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