Wiring a second Diagnostic plug

This topic contains 19 replies, has 5 voices, and was last updated by Chris (agentcrm) 9 years, 6 months ago.

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March 17, 2015 at 11:46 am #2843
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?
March 23, 2015 at 3:55 am #3248
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.
March 23, 2015 at 10:30 am #3255
VRSenator065
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Now that I think of it, I am pretty sure that’s the way mine is wired.
March 23, 2015 at 3:32 pm #3259
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.
April 4, 2015 at 2:22 pm #3916
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?
April 4, 2015 at 2:48 pm #3917
VRSenator065
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Where’s Dan (VPGTS76) when you need him
April 5, 2015 at 7:12 pm #3981
Chris (agentcrm)
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yeah, speedo’s out by 33% out with 215 R15. Probably closer to 40% with 205 R15.
April 6, 2015 at 3:49 am #3994
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
April 6, 2015 at 9:11 am #4000
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.
April 6, 2015 at 9:26 am #4004
VRSenator065
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Isn’t speed ratio easily adjusted in the ECU, or am i missing something?
April 6, 2015 at 5:10 pm #4070
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.
April 6, 2015 at 9:16 pm #4087
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
April 7, 2015 at 1:22 am #4091
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
April 7, 2015 at 11:52 am #4118
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.
- This reply was modified 9 years, 7 months ago by Chris (agentcrm).
April 10, 2015 at 2:21 pm #4446
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.
April 12, 2015 at 5:55 pm #4553
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 9 years, 7 months ago by VPGTS76.
- This reply was modified 9 years, 7 months ago by VPGTS76.
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April 14, 2015 at 9:58 am #4734
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.
April 21, 2015 at 2:23 pm #5192
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…..
May 2, 2015 at 2:53 pm #6138
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.
May 10, 2015 at 8:47 pm #6634
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

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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