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Thread: BCM speed limiter

  1. #1
    Tuner
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    BCM speed limiter

    I was reading that the BCM has a speed limiter in it as well. If so this would explain some of the traction control and cruise control issues people find after they change gears and/or a large enough tire size swap.

    Has anyone (short of going to the dealer who always tell me to take a hike) find a way to adjust anything in the bcm? I have an email off to WAMS but not sure they are into anything out of the basic "turn seat heaters on" and "add fog lamp stuff" which is cool, but not what I need.

  2. #2
    Advanced Tuner IARLLC's Avatar
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    Aug 2016
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    NO BCM control. I have been begging for years.

    Which GEN? With GEN5 PCM gets BCM speed limit via GMLAN. If you don't want the BCM's opinion, just go to Speedo>Limiter>General>Source>GMLAN and switch it to Calibration. Now the PCM will limit speed based on the PCM's calibration.

  3. #3
    Tuner
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    Copy that. And that is how I have it (2018 gen5)...
    but the traction control will still kick on really easy and the cruise control doesnt work. There is either an abs/tc bit in the ecu/TCM that has not been unlocked (I opened a ticket a while ago) or the bcm being a different calibration for gears and tires is causing a hiccup.
    Trifecta says they have it worked out. And their customers verify it, trifecta isn’t saying what they do so I’m not sure. They also say they can tune the transmission with out an unlock so I’m not clear as to what their voodoo magic is.

  4. #4
    Tuner in Training
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    In for any info you get. Planning on ordering 4.56 gears maybe next week.

  5. #5
    Tuner
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    Quote Originally Posted by IARLLC View Post
    NO BCM control. I have been begging for years.

    Which GEN? With GEN5 PCM gets BCM speed limit via GMLAN. If you don't want the BCM's opinion, just go to Speedo>Limiter>General>Source>GMLAN and switch it to Calibration. Now the PCM will limit speed based on the PCM's calibration.
    Gen 5. I have it set to calibration but the cruise is confused and won’t work because it’s controlled somewhere else. A ticket was started apparently it’s a box that hasn’t been unlocked yet.