Mk2 Scirocco 1.8 20vt with DTA ECU - Tacho/ Speedo questions

Discussion in 'Throttle bodies & non-OEM ECUs' started by J66KE B, Oct 5, 2016.

  1. J66KE B Forum Member

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    Hello people first forum post here and hoping you can all share some knowledge! I've done a lot of searching through old threads to find out as much info as possible before posting, but still have a few unanswered questions.

    Ok so I own a Mk2 Scirocco with an APX 1.8t conversion running a DTA ECU... both the tacho and speedo are not working, so from what I've read so far I need to:

    - Buy a tacho converter to convert the digital signal from the ECU output to an analogue signal going into the stock Scirocco instrument panel - Q1: Can anyone recommend a converter they have had good experience with? It sounds like these are universal, is that correct?

    Q2: I have read on one very very old post that the tacho in late Mk2 Golf instrument panels changed to digital, can anyone confirm this & with more info if possible?

    Bit of a long shot but.. Q3: My stock Mk2 clocks are non MFA. However if I replaced the instrument cluster panel with a unit that has MFA would my DTA ECU be able to output to it? (I bought the car already converted and there's no paperwork to tell me the ECU model, I will be able to get this info this weend when the dash comes out and I can get to it!)

    I have a gearbox from a Mk4 Golf GTI - From what I've read this could either be an 02A or 02J? (please correct if I'm wrong), so I need to take the speedo cable from the gearbox to the speedo clock. Q4: Will the clocks give an accurate speed reading as the gearbox is different?

    Hope you can help!

    Jake.
     
  2. J66KE B Forum Member

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    Also is anyone able to tell me how I can figure out exactly which gear box is fitted! lol
     
  3. rubjonny

    rubjonny Administrator Staff Member Admin

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    1. Speak to sparrow, he may be able to change the ecu output to suit mk2 clocks :) otherwise yes you'll likely need a tacho adaptor, same unit as used on MK2 20v conversions:
    http://www.clubgti.com/showthread.php?267196

    2. only the digifiz clocks use the digital signal and are compatible with the 20v tacho output. early/poverty clocks can be modified quite easily to use the digital signal, but the late/MFA units are a lot more tricky if not impossible to convert

    3. nope, same tacho signal for all non-digifiz petrol clocks

    4. if its a 5 speed cable shift yes its an 02a or 02j. either way you need a mk2 1.3 speedometer cable, unscrew the 3 pin plug off the back of the speed sender and the 1.3 cable fits right on and work perfectly :)
     
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  4. rubjonny

    rubjonny Administrator Staff Member Admin

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  5. J66KE B Forum Member

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    Cheers for the reply jonny :thumbup:

    Ok so I've got as far as removing the clocks and most of the dash panels (lots of other work to do other than the speedo/ tacho!) and have discovered that there is in fact no speed sender cable, I've already ordered a Mk2 1.3 cable so will get that fitted as soon as it arrives. I remember a post on another forum that reports certain issues with this setup, extract below:

    A "To drive the Golf 2 speedo is very straightforward and means removing the plastic hall sender device from the top of the box, simply by unscrewing it and screwing on the speedo cable from a Mk2 1.3. This is available under part number 192 957 803, although at 1200mm long, it can be a little short. We have seen the cable from a SEAT Toledo used, which is 1260mm long and this is available under part number 1L0 957 803L.

    With the Golf 2 1.3 cable, we have experienced problems with pattern cables from motor factors that seem to run tight internally and cause needle flicker and cable rattle. The drive ratio from a 02A/J box is wrong for the original speedo as the 020 red gear has 15 teeth and the 02A/J gear has 13 teeth.

    The neatest way to cure this is to use the early Golf Rallye MPH mechanical drive speedo, which costs 102 and was designed for an 02A box."


    -------

    Onto the tacho - I've been reading through an old thread started by Sparrow with lots of info, it's quite a bit to work through if, like me, you are new to all of this and not to clued up on wiring diagrams and electrics. But after reading over a few times I've got a much better idea. I'll get in touch with him as suggested.

    Thanks again for your help :)
     
  6. rubjonny

    rubjonny Administrator Staff Member Admin

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    Good point there, since its a scirocco maybe a mk1 1.3 cable would be better!
    as for the speedometer itself a big block mk1/scirocco clock set will work fine on the 02a/j there is no need to buy one from a rallye. the rallye uses the same part number speedo as a mk2 16v!
     
  7. J66KE B Forum Member

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    Ok so I've found a site that sells them - Bottom of the list as I need the push on connector.

    So just so I am sure - the reason I'd be going for a Mk1 speedo cable is purely for the length being 1600mm? as a Mk2 Golf speedo may be too short at 1200mm.

    So far when searching for parts like this I usually end up on vwheritage (most of the useful bits are sold out!) or ebay - Are there any other sites you can recommend?

    Cheers
     
  8. rubjonny

    rubjonny Administrator Staff Member Admin

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    yeah otherwise the fitment is the same both ends, for the LHD mk1 they use the same cable as the MK2 its just the RHD ones that differ. See how you get on with the MK2 one anyway, I always route the cables along the bulkhead behind the engine rather than in front so you may find the shorter cable is an advantage when doing that :)

    gsf used to sell gemo brand cables which are good gear, also VW classic parts are redoing some of the cables and often they end up cheaper than aftermarket can order from classic parts via from deutsche parts or vw heritage
     
  9. J66KE B Forum Member

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    Ok so a little update - My speedo cables have turned up now so I'll see which one fits the Scirocco best and update as to how I get on.

    Sparrow has also put me in touch with a guy that makes a signal converter which will allow me to use my DTA ECU tacho output signal to drive the stock Mk2 Scirocco/ Golf tachometer - I should be getting hold of this in the next few weeks so will keep this thread updated with the results.

    Thanks again jonny for your help getting me this far! :thumbup:
     
  10. rubjonny

    rubjonny Administrator Staff Member Admin

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    awesome sauce :)
     
  11. J66KE B Forum Member

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    Ok so I've been waiting for the guy to get back to me when he's finished making a batch of tacho converters but still heard nothing back - A little more reading has suggested that this one will work, so ordered one and now need to get it fitted.

    Jonny - Do you know where I can find a wiring diagram for the two connectors that go into the back of the instrument panel? As I'm unsure where the tacho wire needs to go.

    I've had a look through your diagrams on google drive and have looked at 'g2complete90' page 11 (Fig 9, A-C 32-33) Which is a diagram for the instrument cluster (hopefully this is the right diagram!) but it looks like there's 4 wires for the tach? Although really I have no idea of how to make sense of it lol
     
  12. rubjonny

    rubjonny Administrator Staff Member Admin

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    for the tacho best place to splice it to is the wire for it on the engine loom, its the red/black wire to D/26.

    since you have a scirocco the 90spec mk2 diagram is no use, the one you want is jetta89.pdf. plus this should help you as well:
    http://www.clubgti.com/showthread.php?219775
     
  13. J66KE B Forum Member

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    Ok so just to be sure, usually on a standard car the wire for the tacho goes from D/26 on the back of the fuse box and then runs to one of the instrument cluster connectors?

    So I need to remove the wire running to D/26 on the back of the fusebox and splice it to the tacho converter output wire?

    (if I've completely got the wrong end of the stick please bear with me, I'm new to this lol)
     
  14. rubjonny

    rubjonny Administrator Staff Member Admin

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    yep factory it goes:
    coil -> D/26 -> B/19 -> clocks

    you don't have to remove the D/26 wire, just cut it to a decent length and tap it to your adaptor :) for an ignition feed D/2, D/7 or G spade 2 or 5 will do you, earth to the claw above the fusebox or tap it to the thick brown on the D plug.

    you could insert the tacho adaptor to the clock wire if you wanted, tap it to live and earth there as well. just means if you change the engine management later and it puts out a proper 12v pulse you would have to take the adaptor out again, rather than just take out the old engine loom with adaptor still on it and swap it for another.
     
  15. J66KE B Forum Member

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    Ok great, so currently D/26 is useless as there is no 12v pulse for it to send a signal to the tacho.

    So I'm going to cut the wire going to D/26 and tap it to the Tach Output wire on my adapter. G spade 5 is free so I use that for the ignition feed and also have space on the claw to earth to.

    Sparrow is posting me some terminals for my ECU, working away all next week but hoping I can get this done on Sunday!

    Ps. Just a few more questions lol

    What is the difference between splicing and tapping?

    You mentioned I could tap the earth to the thick brown on the D plug - Where is this?

    EDIT:

    Ok so I've taken the fusebox out to see what's happening - Turns out the red/black wire from D/26 runs to a relay first and then back behind the fusebox with the rest of the wires - Is this normal? Pic below

    [​IMG]
     
    Last edited: Sep 18, 2017
  16. rubjonny

    rubjonny Administrator Staff Member Admin

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    splice = tap :lol:

    the relay you have found is for the increased idle valve control relay, which is no longer required. very handy as it has all the feeds you need to it. black is ignition live, brown is earth and red/black is your tacho feed to D/26 :)

    If you have a word with Chris Bellman on facebook he can build you a tacho adaptor into a VW relay housing, and it might be possible to build it so it plugs straight into that relay holder. if so all you would need to do is tap your ecu tcho wire to the black/brown.

    if you already have your adaptor though no worries, you could chop the relay wires off and re-use them for your adaptor and bin off the brown/black. The relay holder might be handy for you, could pop an ecu/coil power relay in it, just need to get yourself some standard latched 6.3mm spade terminals :)
     
  17. J66KE B Forum Member

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    Ahh I already have an adaptor to use but one built in to a relay housing sounds awesome! Although I still haven't got round to fitting it, so am yet to see if it's going to work. I am hoping to get round to it early this week!

    I have managed to get a few other things done as far as the speedo goes - I decided to try the 1600mm cable first (originally for the Mk1 Golf 1.3) but it was way too long. I persevered and managed to loop it behind the clocks and it plugged it in, the speedo did work....kind of, the needle was roughly indicating the correct speed but was shaking like mad, I did some testing and as I thought it is due to the loop in the cable.

    Another thing I uncovered whilst on the test drive...the odometer wasn't working [:|] So...I did some googling and found a useful forum post and link (courtesy of rubjonny of course :thumbup:), link to the guide I used is here. The good news is, it worked. But f**ing hell what a nightmare! All very nice and easy to follow until the final step of gluing the metal cog and putting it back in. The trick was to use a tiny drop of glue, as if you use even slightly too much it dries almost instantly and blocks the hole meaning you have to take it out and clean it before trying again. It's also down to a bit of luck when you push the rod back through it and the support hole on the other side. Anyway 2 hours later it's fixed and the instrument cluster is back together!

    Next step is to get the 1200mm speedo cable in and wait for a dry day so I can get the car out of the garage and test it.

    Jon - A question regarding instrument cluster lighting, the backlights on mine are not working. I changed all the bulbs, checked the fuses and all check-out fine, but still no lights. Can you suggest the next thing to check? I was thinking maybe it could relate to the dimmer on the headlight switch?
     
  18. rubjonny

    rubjonny Administrator Staff Member Admin

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    the dimmer is a good place to start if non of the other dash switch lights are working, they can fail. give the wheel a wiggle mine kills the lights if you turn it too far :lol: the grey/blue wire is the illumination, it starts at the headligth switch and feeds all the rest of the dash. make sure this is all good, and you see 12v at the switch end with dimmer at full
     
  19. J66KE B Forum Member

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    Thanks Jon I'll do some troubleshooting later this evening :)
     
  20. rubjonny

    rubjonny Administrator Staff Member Admin

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    also if its a later rocco the dash lighting feed is fused unlike earlier models. check the number plate lights are working. if not change the fuse and see if the dash lights come back :)

    if they dont see if the fuse has popped again, if so thats a clue the dash lighting is shorted, or possibly the plate light power. a good place for shorted dash lights is the radio area, if someone has bodged the plug often the grey/blue dash lighting feed is just left floating about behind the dash and can short
     

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