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  1. #1
    Join Date
    Mar 2002
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    Chester
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    LS1 efi questions

    Hi All,
    Just sorting out wiring for the GM PCM.
    Can anyone please help with the following questions....
    VSS output - what is this signal type and is it compatible with the ETB speedo?
    Engine temperature - input is to PCM, is there another port on the engine for water temperature gauge?
    Fan 1 and 2 outputs - use either to control rad fan?

    This is just the start of the mithering.....
    Stan

  2. #2
    Join Date
    May 2004
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    Cowbridge, United Kingdom
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    Hi Stan,
    just gone through the same pain myself.
    I haven't tried the VSS output but I guess it's a hall effect so should work on an ETB or in my case Smiths electronic speedo.
    You will find that at the rear of the right hand head (drivers side) you have a plug M12 I think remove that and put your coolant temp sender for your gauge in there.
    I'm only using one fan as well, I believe you can configure HP tuners to use either fan output.
    My fan hasn't cut in yet so I can't be sure if I've got that right.
    Oil pressure just remove the OEM one at the back of the engine and use adapters to fit yours, the PCM is happy without that input.
    If you want oil temp you can tap the sump plug or the cooler bypass housing above the filter on my LS2.
    Hope this helps.
    Kev Davies
    South Wales Area Rep. UKCC Membership Secretary
    DAX Mk4, 383 Chevy Stroker, Tremec. SOLD
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    Dax De Dion LS2 and T56 IVA'd June '17 SOLD
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  3. #3
    Join Date
    Mar 2002
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    Chester
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    Thanks Kev. I posted on LS1Tech and was told the output is square wave, possibly 5v peak to peak so a pull up resistor may be needed. I'm trying to get more info also for tacho output.
    Good pointer for the temp sensor....the same port on the other head (at the front) is the ECT sender.
    I have EFILive Scan and Tune and I'm investigating what bits and pieces are needed for out of vehicle configuration....
    Stan

  4. #4
    Join Date
    May 2004
    Location
    Finchampstead, Berkshire, UK.
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    Pull up option available in the ECU

    I use EFI Live (as do a few others on here), shout if you've got any questions

    Jim
    GD Mk3 Jag based
    Supercharged LS1
    GD J1M

  5. #5
    Join Date
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    Thanks Jim. You may regret the invite to ask questions...😀
    At the moment I'm just sorting out wiring just to make sure I don't damage the pcm. Just need to understand what each out put requires for compatability.

  6. #6
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    Mar 2002
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    Chester
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    Jim, have you matched up the pcm with speedo and tachometer? I intend to use ETB instruments so any wiring advice appreciated.
    Thanks, Stan

  7. #7
    Join Date
    May 2004
    Location
    Finchampstead, Berkshire, UK.
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    Hi Stan,
    Yep mine all work fine (smiths stuff though, not ETB). I've got a spreadsheet on my PC somewhere with a bunch of wiring info on it, I'll dig it out tomorrow and send it over if you PM me your mail addy (I'll include a copy of my tune if you want to look at some of the segments etc)

    Cheers

    Jim
    GD Mk3 Jag based
    Supercharged LS1
    GD J1M

  8. #8
    Join Date
    Dec 2015
    Location
    Fairseat, Kent
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    60
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    33
    Jim, could you send the wiring info to me please? Also, do you happen to know what the tachometer engine side connector needs to be connected to bearing in mind I have 8 individual coil packs (I believe you normally connect to the old style single coil?). Thanks, Chris
    Very junior apprentice.

  9. #9
    Join Date
    May 2004
    Location
    Finchampstead, Berkshire, UK.
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    Hi Chris,

    No probs, I’ll blow the cobwebs off it and send it over.

    My Tacho is driven from an ECU output, I’ll highlight which wires from the ECU to use (I assume the Painless wiring loom will have kept the output connected and in place, but easy to check once I give you the details).

    Cheers

    Jim
    GD Mk3 Jag based
    Supercharged LS1
    GD J1M

  10. #10
    Join Date
    Dec 2015
    Location
    Fairseat, Kent
    Age
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    Posts
    33
    Thanks very much.
    Very junior apprentice.

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