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Thread: E67 Auto to Manual tune

  1. #1
    Tuner in Training
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    E67 Auto to Manual tune

    I want to change a 2008 Trailblazer ECM from Auto to Manual. I know how to do this with the P10 and P12, but the E67 is configured for a TCM. So by default, it's looking for the VSS signal on GMLAN. If I set the cal to "manual transmission" will it know to look for the VSS direct to the ECM?

  2. #2
    Advanced Tuner Shrek's Avatar
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    Quote Originally Posted by limequat View Post
    I want to change a 2008 Trailblazer ECM from Auto to Manual. I know how to do this with the P10 and P12, but the E67 is configured for a TCM. So by default, it's looking for the VSS signal on GMLAN. If I set the cal to "manual transmission" will it know to look for the VSS direct to the ECM?
    Not exactly ... it is always a good starting point to begin by reviewing the appropriate GM Service Manual.

    ECMs may receive VSS input in 3 ways:
    • GMLAN (used in many, but not all, automatic transmission vehicles)
    • REP TOS (used in some automatic transmission vehicles)
    • direct pulse from VSS (used with manual transmission vehicles, and some 4WD vehicles were the VSS in mounted in the transfer case)
    The 2008 Trailblazer ECM received a REP TOS signal on C3 pin 66 - from the T42 TCM. If you switch the ECM to a manual transmission configuration, wire the VSS High input to ECM C3 pin 66, and the VSS Low input to ECM C3 pin 67.

  3. #3
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    Quote Originally Posted by Shrek View Post
    Not exactly ... it is always a good starting point to begin by reviewing the appropriate GM Service Manual.

    ECMs may receive VSS input in 3 ways:
    • GMLAN (used in many, but not all, automatic transmission vehicles)
    • REP TOS (used in some automatic transmission vehicles)
    • direct pulse from VSS (used with manual transmission vehicles, and some 4WD vehicles were the VSS in mounted in the transfer case)
    The 2008 Trailblazer ECM received a REP TOS signal on C3 pin 66 - from the T42 TCM. If you switch the ECM to a manual transmission configuration, wire the VSS High input to ECM C3 pin 66, and the VSS Low input to ECM C3 pin 67.
    Great, thanks for the help!

  4. #4
    Please expand on the transmission type change to "manual transmission". I don't see this in the software.

    With the VSS inputs to the ECM, and no other changes, I am unable to get a VSS signal.

  5. #5
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    Quote Originally Posted by s10Wildside View Post
    Please expand on the transmission type change to "manual transmission". I don't see this in the software.

    With the VSS inputs to the ECM, and no other changes, I am unable to get a VSS signal.
    On the vehicle I was working on (2008 trailblazer) the TCM has a dedicated line to the ECM for vehicle speed. To convert manual, I had to run the VSS direct to this ECM wire, and then find a low pin on the PCM for the other wire.

    The trans type is a pull down menu on the "Trans" tab.

  6. #6
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    Did You get the VSS working correctly?
    1999 Chevy S10 Blazer 4dr w/2008 LS3 Corvette 6.2L mated to a t56.

  7. #7
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    No complaints from the customer.

  8. #8
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    Any updates on this?