HomeForumsTechnical – GeneralECU & TuningWiring a second Diagnostic plug

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  • #2843
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    Chris (agentcrm)
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    As the title suggests, I need to add a second diagnostic plug. I’m 99% finished an L67 conversion into my VR, I’m using the VS loom & computer meaning I can’t read the ECU through the standard plug. I went an aftermarket chip to avoid doing this so soon but the speedo is so far out it’s rediculas. (60 is 80 of the dial)

    So how do I do this or do I need to get a BCM simulator?

    #3248
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    delcowizzid
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    You should be able to match up the wires at the under dash plug that joins engine loom to dash loom and have the stock diagnostic socket work as normal.

    #3255
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    VRSenator065
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    Now that I think of it, I am pretty sure that’s the way mine is wired.

    #3259
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    dave
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    Should not be too hard. Pretty sure only 4 wires needed in the 16 pin data link connector. 12 volt power pin 16 and an earth pin 4 or 5 and the GMLAN Serial Data Bus+ pin 6 and GMLAN Serial Data Bus- pin 14.

    #3916
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    Chris (agentcrm)
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    Right, so I’ve got EFI live V4 working, but not Tunerpro that I need to adjust the speedo.

    Are there different VSS drive that would throw the Speedo out?

    #3917
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    VRSenator065
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    Where’s Dan (VPGTS76) when you need him :)

    #3981
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    Chris (agentcrm)
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    yeah, speedo’s out by 33% out with 215 R15. Probably closer to 40% with 205 R15.

    #3994
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    delcowizzid
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    Is the speed out due to diff gears if so jaycar Speedo corrector or similar inline from ecu to dash is the fix

    #4000
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    Chris (agentcrm)
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    It shouldn’t be, though I didn’t think of that. I did change diffs but it should have been a 3.08 High performance I pulled out of a wreck when I ditched the sunroof. Though using a speed / gear calculator I’m not sure it’s different.

    If I need an adjuster box I’ll need to put it before the ECU so that see’s the correct speed as well.

     

    #4004
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    VRSenator065
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    Isn’t speed ratio easily adjusted in the ECU, or am i missing something?

    #4070
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    Chris (agentcrm)
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    Yup, takes 20 seconds. If I could get my tuning program to work with either of the 2 cables I have.

    EFI live V4 doesn’t have tuning capability which is a pain as I got that working the other day. Tunerpro has always been a pain to get working but it’s free.

    Kalmaker doesn’t seem to be an option as I don’t want to be spending $$$$ to fix 1 cars ECU.

    #4087
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    Chris (agentcrm)
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    Progress, ish.

    I remembered about a bunch of data files I had for Tunerpro from the OSE plug in. Loaded them in and managed to get the Data acquisition side kinda working. gauges where bouncing around all over the place but that’s about all I’ve ever had them doing.

    Still no luck getting the tuning side working

     

    #4091
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    delcowizzid
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    Vs ecu just passes speed data straight through the ecu to dash just fit the corrector inline after ecu and the box will shift normal but Speedo will read correct.if you fit it before ecu you shifts will need tuning

    #4118
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    Chris (agentcrm)
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    Almost, except my issue isn’t just the speedo itself reading wrong. I’ve used EFI Live to read a full dash straight from the diagnostic plug, as I was wondering if it was an issue in the dash itself. It isn’t, the ECU output was out by 33%

    Also you can change the road speed in the bin file.

    #4446
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    Chris (agentcrm)
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    Something similar to progress.

    I got the OSE Flash tool working and managed to download the BIN & CAL files. I just can’t upload the modded files back to the memcal. I’ve messaged Mace via fb as it’s one of their memcals. I was also hoping to get the files from the stock chip but no luck there.

    #4553
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    VPGTS76
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    HI MAte,

    ONLY LSx ECU can adjust speedo….

    VN- VP Direct feed

    VR  + Pass thru unless its LSx

    I am tipping new diff has 3.9 as that would make it 30% out.

    Jaycar box is the way to go put it on the Purple / white wire on dash side of plug.

    Also to get OBD2 plug going ensure black/ red (Diag Port DATA    ECU = A8)  and white /  black ( Diagnostic Port   ECU = A9)  wires on ecu loom and main loom line up. balance of wires are part of dash loom.
    Thanks

    Daniel

    • This reply was modified 6 years ago by Profile photo of VPGTS76 VPGTS76.
    • This reply was modified 6 years ago by Profile photo of VPGTS76 VPGTS76.
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    #4734
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    Chris (agentcrm)
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    3.9’s would put it out the other way though. Rev’s way higher for speed. Mines low revs massive speed, my commute spends half it’s time at 90kph (2200rpm, 120 kph on the speedo) and the revs match the old diff at that speed.

    In the bin files there is the option to change the road speed calculation, if I could get writing working.

    Tried the Jaycar box, couldn’t make the stupid thing work and my gear shifts are still out anyway.

    #5192
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    Chris (agentcrm)
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    I bought a new VSS and fitted that at lunch time. No change, so either I’ve got a 2.3:1 diff, the memcal isn’t programmed correctly or the VSS wheel on the gearbox shaft is wrong…..

    #6138
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    Chris (agentcrm)
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    Ok, time to eat my own typing.
    I just looked on the ” Unofficial Holden Commodore  archive”

    I was asuming 4th was 1:1 not 0.7:1 overdrive. running the new gear ratio through Osella’s gear ratio calculator that means I have a 3.9:1 diff. I think I’ll put the old diff back in as I only changed it to get an LSD centre, at least for the time being.

    #6634
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    Chris (agentcrm)
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    Well the old Open (unfortunately) diff is back in and the speedo is back to where it should be. :D :yahoo:

    Not sure yet what I’ll do LSD wise yet. Torquetrac (Trutrac knockoff?? or at the same type), KAAZ or another factory cone type.

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