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Thread: LS1 0411 BenchTop Programming harness

  1. #1
    RIP EagleMark's Avatar
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    LS1 0411 BenchTop Programming harness

    I was working on a bench top programming harness last week and took some pictures and notes in case anyone else wanted to make one. There's bits and pieces of information all over but I have yet to see it all in one spot? Procedure is about the same for all PCMs, need power to PCM, grounds and the serial connection. So with this setup you can cut the harness and add plugs to make more PCM plugs for different PCMs.

    I've heard some horror stories of bricking a PCM when doing a full reflash in a vehicle with other modules connected to serial line interfering and seems the safe way is the bench top method. Just tune changes don't seem to be an issue. Heard of some pulling fuses to other module circuits. I don't know all the possibilities and maybe we can come up with a list of does and don't when it comes to full flash?

    So this is for the 0411 PCM that comes in LS1 engine vehicles. They are a little different so watch the wiring! Only 4 -5 wires needed!

    1997 - 1998 only all in the Blue PCM connector.
    Blue Pin 21 Ground and OBDII 4 and 5 ground.
    Blue Pin 20 and 61 +12v Orange wire OBDII Port 16
    Blue Pin 19 IGN +12V Pink wire - key on.
    Blue Pin 58 Serial Green to OBDII Port 2


    1999 up 0411 PCM - LS1, LB7, Early V6 and 4 cyl
    Blue Pin 19 IGN +12V Pink wire - key on.
    Blue Pin 20 +12V Orange wire - OBDII port 16
    Blue Pin 60 Ground Black White Stripe - OBDII Port 4 and 5.
    Blue Pin 58 VPW Serial Data Green to OBDII Port 2.

    OBDII ALDL wiring for GM, some wires are same on all cars and some are different per manufacturer and vehicle with more modules.

    Vehicle OBDII Connector Pin Assignments


    Vehicle OBDII Socket
    SAE J1962 Female


    1. GM CAN (Low-speed, Single-wire). Not used for benchtop harness.
    2. Serial data. Used for bench top harness!
    3. Pin assignments have been left to the discretion of the manufacturer. Not used.
    4. Ground black wire (chassis ground). Used for bench top harness!
    5. Ground black/white wire (Siganl Ground). Used for bench top harness!
    6. ISO 15765-4 CAN High. Not used for benchtop harness.
    7. ISO 9141-2 & ISO 14230-4 K-Line. Not used for benchtop harness.
    8. Pin assignments have been left to the discretion of the manufacturer. Not used for benchtop harness.
    9. GM ALDL (OBD-I 8192bps) Not used for benchtop harness.
    10. SAE J1850-VPW Negative. Not used for benchtop harness.
    11. Pin assignments have been left to the discretion of the manufacturer. Not used for benchtop harness.
    12. Pin assignments have been left to the discretion of the manufacturer. Not used for benchtop harness.
    13. Pin assignments have been left to the discretion of the manufacturer. Not used for benchtop harness.
    14. ISO 15765-4 CAN Low. Not used for benchtop harness.
    15. ISO 9141-2 & ISO 14230-4 L-Line. Not used for benchtop harness.
    16. Fused battery feed orange wire. Used for bench top harness!

    There's 12 volt power supplies used on some commercial bench top harness but I have always stuck with a 12 volt fully charged car battery. TunerCat warns not to use an AC charger on laptop when flashing a PCM in car. EFI Live warns no AC charger to flash as well in car (IIRC when V2 is grounded with external data like wide band). While others say to keep AC charger on laptop while bench top programming. Since I have always used a full charge battery on bench or checked charging system and battery in car, and always start with a full charge on laptop battery and never had an issue I'm sticking to that.

    Flashing in car:
    Vehicle: All accessories off, car alarms off, OnStar off.
    Laptop: Screen savers off, power management off, virus protection off, do not interrupt!

    Here's a good use for an old ECM as an electronics project box. 12 volt is needed to PCM at all times, 12 volt is also needed to Ignition 12 volt power to PCM, some tuning flashes can be done without this but not a full program or VIN number change, this change is saved in vehicle PCM when key is turned off and 12 volt power is still applied. So in keeping with programming just like in a car we have Key On Power like the key switch.

    I used lighted switches so I can see power on and key on.
    Main power switch gets power and sends it to Pin 20 or 20 and 61 of blue PCM connector and to Key On switch and to OBDII Pin 16.
    Key on power switch sends power to blue PCM connector Pin 19
    Ground blue PCM connector Pin 21 or 60 and
    Ground OBDII ALDL port 4 and 5.
    Ground lighted switches.
    Serial data from blue PCM connector to OBDII Pin 2






    A look at inside wiring.



    All done and ready for back cover and mount on the wall.



    Here's the finished equipment ready for bench top programming. Up top is one I built awhile ago for LT1 PCMs.
    Attached Images Attached Images

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

  2. #2
    Wait, that's not an '0411 PCM! Or did you pull the guts out of an LS1-style PCM? The only year you *have* to pull fuses on when programming in the vehicle is the 2003 (I have the fuses to pull if anyone wants them). It's very difficult to brick the LS1 PCMs. I've done about two hundred of them, and don't ever recall bricking one. (Don't get me started on how easy it is to brick the '96-'97 LT1 PCMs!)

  3. #3
    RIP EagleMark's Avatar
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    It's just an old 1227747 box I used to make a bench flash setup with.

    The bricking of PCM in vehicle was a general statement, I wish there was a known list of which ones not to do, or which ones are an issue with full flash?

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

  4. #4
    I can tell you from experience that the '96/'97 LT1 PCMs are very prone to bricking, especially if the flash is interrupted for some reason. I use a modified version of TunerCat for most of my OBD2 flashing, and highly recommend running it only under Windows XP (use the virtual machine in Windows 7). I've been unsuccessful in unbricking them, even after installing the PLCC sockets and flashing two new memory modules. So it's a work in progress trying to get them fixed!

    I have never bricked the LS1-style PCMs, so I can't share much personal experience on those. (I do, however, have several that do not work that I've been ripped off on from various sources...perhaps they have been bricked? Haven't had time to investigate...)

  5. #5
    RIP EagleMark's Avatar
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    Bricking info I was looking for was general, not specific to LS1.

    The only info I have for bricking PCMs is during full flash, other modules seem to interupt when full flash, not just paremter changes flash.

    All my TunerCat stuff is run in Windows XP service pack 3 compatibility mode.

    Low voltage from vehicle batterey or laptop is always an issue during flash.

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

  6. #6
    Fuel Injected! EDZIP's Avatar
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    Anyone have a 1999 and up 0411 pin out diagram?

  7. #7
    Super Moderator dave w's Avatar
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    Quote Originally Posted by EDZIP View Post
    Anyone have a 1999 and up 0411 pin out diagram?
    Try this link for the '0411 wiring information:http://www.lt1swap.com/wiringharness.htm

    dave w

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