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Thread: Turning off vats in an '05 Impala PCM

  1. #1

    Turning off vats in an '05 Impala PCM

    Ok, I posted this in the V6 tuning section with NO help at all. Since I couldn't get a straight answer, I went ahead and purchased the credits to turn the VATS off on this PCM.

    Apparantly, it can't be done. I've tried every which way to turn the thing off, and no matter what I do, the fuel enable won't function. I even went so far as to change the type to PWM so it would work with my ancient VATS system (which is still active) to no avail.

    If I am doing something wrong, please let me know. If I am not, I'm going to be highly upset at losing 100 bucks.

    Link to original post...
    http://www.hptuners.com/forum/showth...752#post186752

  2. #2
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    It doesn't have to be perfect, it just needs to be done in two weeks...

    A wise man once said "google it"

  3. #3
    Tried all that. I actually did that FIRST. Believe me, I wouldn't be posting this if I didn't try it already.

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    Email support then as that thread eludes to.
    It doesn't have to be perfect, it just needs to be done in two weeks...

    A wise man once said "google it"

  5. #5
    Emailed. I really hope this issue gets resolved soon. Getting the PCM to play nice is the only thing left to do on this project

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    Quote Originally Posted by Bill@HPTuners View Post
    That method on the referenced post doesn't work As far as I know the operating system on the PCM must be changed to an earlier version that will allow shuting the VATS function off. Not sure that this will work on an ETC based system though.

  7. #7
    If it doesn't work (which it doesn't), then it needs to be stated by the company, not by the end users. Apparantly I'm not the only one that has had this issue, and it appears to be ongoing.

    Also, flashing an older OS onto the PCM shouldn't have to be the workaround. Even then, there are no guarantees it will work, which would then be even more money wasted, and more people ticked off. As much as I want this project fired up this week, I refuse to spend any more money and buy more credits until I get word back from the engineers on what the issue is and how it can be resolved. I'll do whatever it takes to help out and getting them the info they need, but if it can't be done then something else needs to happen.

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    Quote Originally Posted by sandrock View Post
    If it doesn't work (which it doesn't), then it needs to be stated by the company, not by the end users. Apparantly I'm not the only one that has had this issue, and it appears to be ongoing.
    Its working fine, in the scanner log you sent the vats pid is stating vats ok so thats not the issue and its likely something else. Aren't swaps fun
    It doesn't have to be perfect, it just needs to be done in two weeks...

    A wise man once said "google it"

  9. #9
    this is the first time i have heard of it not working, we had some bugs on some OS's where GM had changed the logic of VATS type between 0 and 1 for PWM/Serial etc. but afaik it works if you set to PWM and disbale the DTC's. If the scanner VATS status shows ok and you have type set to PWM then it must be something else.

    other things could be crank sensor issue, electronic throttle issue, traction control.
    I count sheep in hex...

  10. #10
    As far as codes go...I did pick up two codes with the factory setup. The first was U1000...which I expected since the PCM is all by itself. The second one was P0520...oil pressure sending unit malfunction. I "threed" both of them since my application does not use them, but as I have learned about code deletions, just because you tell the PCM to shut up about it, doesn't mean it will ignore it. I have a solution in the works for the U1000 (I hope)...I'm researching whether or not the oil pressure issue will cause a no-start. If so, I'll have to trick it and go from there.

    Now, another odd thing...and I stated this to Bill in email correspondance...the original, unmodded file still gave me the "ok" VATS status bit, which in my laymans thinking shouldn't happen at all since there are no VATS or BCM systems tied to it. I'll be more than happy to post that scan showing that, along with the original tune.

    The '05 Impala PCM is setup for an L36, which my project is setup as too. I don't have the ETC setup, and this PCM shouldn't be expecting it, so that's not what is wrong. I could try swapping the ICM plate, but I doubt that's the issue too. I honestly think this PCM wants to see something else in the dataline before it will allow the injectors to pulse. As such, I bought a VATS/PK2/PK3 bypass kit for remote start applications, and ties into the dataline, not the fuel enable circuit. This should act as a surrogate BCM for fuel purposes only.

    Thanks for your guys help so far. I still think it's in the programming somewhere, especially since the original file is lying about the VATS status. To me, it shouldn't stay "ok" if there are no security measures in place.
    Last edited by sandrock; 09-22-2009 at 05:08 AM.

  11. #11
    the unmodded PCM will probably show the VATS as being ok as that status is only used for PWM VATS. Setting the type to PWM bypasses serial VATS completely so it's not even checked in the fuel disable calculation.

    just out of curiosity, do you have a MAF on this vehicle?
    I count sheep in hex...

  12. #12
    The original file had serial security as its setting. I changed it to PWM in my modded file as that is the same type as the VATS system my car has. That's the big reason why I reloaded the original file and then ran a scan on it, to see if the VATS status bit would change, and it did the exact same thing. That's why I am wondering if the VATS status might be backwards, at least with this PCM.

    I am running a MAF, and the table should be fairly close to what I have installed. For craps and laughs, I unplugged the MAF altogether just to take it out of the equation and I still had the same issue.


    I did some lookups of the two codes I did happen to throw, and neither one appear to cause a no-start condition. I was thinking maybe the oil pressure DTC might could act as a fail-safe, and on older models it is tied to the fuel pump relay. But the scans show fuel pump is commanded on during cranking, but the injectors aren't pulsing (if they do, its only for a few moments at the beginning, then to nothing). Anything available in the scanners VCM control I can control, so my wiring is good.

  13. #13
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    Did you ever get this resolved