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Thread: GM Quad Driver Chart C3 and P4

  1. #1
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    GM Quad Driver Chart C3 and P4

    From time to time discussion turns to using code and ecm that were not originally put together. A common example might be putting $58 into a 7730. This chart is from an old GM training manual and could be used to help identify where to connect pins for outputs when trying to migrate code between ecm's or just to help diagnose a problem with a Quad Driver Module.
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    Hey 1Project,

    I am getting QDM failures posted both by my scan tool as well as TunerPro RT.

    What is weird is that it doesn't show up as a trouble code... just as a line item saying "quad driver module failure" YES.

    Any idea how a person should go about debugging this?

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    What kind of scan tool? This is probably a flag in the data stream... need to look at the ALDL definition to know. Is anything not working? QDM's control outputs.

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    Both my MPSI scanner (old) and Tuner Pro both show QDM Fault A/B= Yes. This does not show up as a trouble code on either device... just in the data stream (bit mask in tuner pro) they show up.

    Tranny is acting super wacky in my opinion- not downshifting right when I want to engine-brake. Before I dig further into that I want to find out if the QDM thing is real or not.

    OK- I'll try to find the ALDL definition (is this where the stream is defined?) and see what I can figure out.

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    A bit of searching and can't find a definition for the ALDL data stream. Should I be finding that somewhere? I assume that data is used to create things like the adx file. I wouldn't mind seeing what is all in the stream if it is available.

    Also was searching for a 6395 schematic... with no luck. Any pointers on finding these two items?

    Thanks man.

  6. #6
    billygraves
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    Last edited by billygraves; 06-30-2019 at 06:18 PM.

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    Billy, wow... would love to chat about those days in GM!! I got the MPSI about 15 years ago on a closeout from an injector place. Yep- the back of it says Sterling Heights MI!

    I stayed the night in the Corvette plant back in 91 or so during the GM Sunrayce... those were the days!! Bob Stempel...

    So what you are saying is that the scanner might not be providing good info on this... right? My PCM is 16196395/16197427 . If I could find out that these "fails" are false- it would be great ... but I am experiencing some transmission problems so I am suspicious about these things.

    I wish I could get my hands on a schematic for the PCM... so far havent been able to find one yet.

    Thanks!!!!

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    1Project,
    When I was @ GM in 94, I asked the Powertrain Group Software personal about these quad drivers. The diag codes will only function IF the actual quad driver has a software output to the internals telling of a failure. This was in 94-95. I inquired about this to include this in the OBD-2 diagnostic codes we were developing. If the Controller has the Good or $$$ drivers, they have diags and an output for this, the less $$$ don't. That's what I remember anyway.
    That matches what I remember from STG and the training centers. The software may be there but the hardware isn't always compliant. The scantool won't report a code if the hardware doesn't support it. After I llearned more about the code I associated that phrase with the codes actually being enabled.


    You are looking at MPSI??? That was in Sterling Heights MI. Anyway. When I was the Tech-1 Powertrain person at GM in 90-94 the ECM's sometimes had good info with these quad drivers. Sometimes not so good. I have NO IDEA what ECM or vehicle you have, but some ECM's I could NOT use the QUAD driver info. Some was because one of the 4 Quad driver pins were not used in a certain car/truck line.
    7427 PCM? My thought was to check data stream definition for the particular mask. Seems to me that if trouble codes are not reported that confirms the hardware can't be trusted.

    Kevin... there are original text files around that contain the datastream definitions. Not sure where to find them anymore but the extension was .adl and they used to be in a big zip file. I have a copy at home that I can upload if someone doesn't post a link. 6395 is a C3 (no QDM codes). Find the mirror of Ludis' page and see what's there.

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    Last edited by billygraves; 06-30-2019 at 06:18 PM.

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    Hey 1Project... can you just clarify what you mean by this statement: 6395 is a C3 (no QDM codes). ?

    Thanks!

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    Thanks for this info BillyGraves! Thanks!!!

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    I found out what C3 means from Ludis' site-- He states that 6395 is not C3 though as far as I can tell (here-> http://www.exatorq.com/ludis_obd1/p4xref.html )

    Anyhow- still cant find a schematic :( --

    I basically need to figure out if this quad driver thing has ANY validity b/c if those errors are false.. then my tranny is shot and I gotta take it out and send it back to Chicago ... so that is why I am obsessed with this quad driver stuff at the moment!! :) THanks all!! Sounds like it would be easiest for me to find someone with a tech 1...

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    If a data stream has a bit status for a Fault in a particular QUAD driver, it could STILL BE INCORRECT. Only the Tech-1 is correct with the QUAD drivers IF they were displayed on the T-1 Screen.
    Understood. I was looking for fault code presence in datastream. Fault code should not set when status could be incorrectly reported. If fault code is not included in data stream then the assumption is active status bit cannot be trusted. If fault code is reported then we cannot discount status bit.

    I dug out audio recorder at a dealership and people laughed. I'd let car owner borrow recorder then bring it back after problem occurs. Saved me from driving for free.

    I basically need to figure out if this quad driver thing has ANY validity b/c if those errors are false.. then my tranny is shot and I gotta take it out and send it back to Chicago
    Sorry about confusion on ECM/PCM type. Was thinking that number was same as manual trans equipped truck which had C3. I believe the 6395 PCM you have was replaced by the 7427. But diagnosing trans doesn't require digging through data or viewing QDM info. If the problem is slipping you'll likely have burnt/bad fluid to accompany. If the problem is electrical you can check voltage / resistance on solenoid control lines to confirm pcm is controlling properly. What is symptom? Do you have Factory Service Manual to assist with diagnosis?

  14. #14
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    Thanks 1Project,

    The problem is this:

    Drive in 4th at 50MPH
    Let off gas,
    Truck engine brakes a little
    manual shift into D3
    Truck seems to go into neutral (less engine braking - still going about 50)
    manual Shift into 2nd,
    Can rev gas a little bit and it is like it is in neutral
    Rev up to 2500 and boom... trans shifts into 2nd.
    If I don't do this Revving routine, it will NEVER shift to second... will seem to coast in "neutral" ALL the way down to stop

    That's my frustrating problem! :)

    I have a video of this as well as a TunerPro trace if anyone is really interested :)

    Need to know if it is somehow electrical or chip related or if this tranny has to come out (again).

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    billygraves
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    Last edited by billygraves; 06-30-2019 at 06:18 PM.

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