auto tranny from D to M on go and downshift causes 2 gear downshift
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2008-2013 Cadillac CTS General Discussion Discussion, auto tranny from D to M on go and downshift causes 2 gear downshift in Cadillac CTS Second Generation Forum - 2008-2013; 2010 CTS4 3.6. For example, driving at 40 MPH in D. Move shifter to M and dash says "4." Then ...
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    BIC
    BIC is offline Cadillac Owners Member
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    auto tranny from D to M on go and downshift causes 2 gear downshift

    2010 CTS4 3.6. For example, driving at 40 MPH in D. Move shifter to M and dash says "4." Then manually shift down one to 3 and it goes to 2. Once it's done that, feature works OK thereafter, shifting down one gear at a time. Typical reason for this scenario is going down a hill. If go directly to M while stopped, no issues; only if shift to M on the go.

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    hauler's Avatar
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    Re: auto tranny from D to M on go and downshift causes 2 gear downshift

    According to my manual, the pull down engages sport mode, which obviously wants the engine in a higher rev range.

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    BIC
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    Re: auto tranny from D to M on go and downshift causes 2 gear downshift

    Quote Originally Posted by hauler View Post
    According to my manual, the pull down engages sport mode, which obviously wants the engine in a higher rev range.
    Switching from Drive to Manual, puts it in Sport mode, which does increase relative RPM in each gear compared to Drive. Pulling it down, engages Driver Shift Control (DSC). Then, RPMs are controlled by the shifter (see quote below). There are some very fine distinctions in semantics in the owner's manual on this topic which makes it a bit confusing.

    Regardless, the Sport mode increase in RPM doesn't account for the double shift down because once in DSC mode, it should only respond to manually selected shifts (unless they're potentially damaging shifts, then the command is ignored {thought I saw that somewhere, but can't find it now}). What concerns me is these double downshifts lead to a high-revving engine and chirping tires. The following two sentences on page 8-29 seem to say my issue should not be happening. While in DSC:

    "The transmission will only allow you to shift into gears appropriate for the vehicle speed and engine Revolutions Per Minute (RPM). The transmission will not automatically shift to the next lower gear if the engine RPM is too high, nor to the next higher gear when the maximum engine RPM is reached." Thank you for your response.

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    jeffc83's Avatar
    jeffc83 is offline Cadillac Owners Connoisseur
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    My CTS never skipped a gear nor does my LaCrosse.

    Does it happen all the time? If so, I'd bring it into the dealer and replicate it with one of the techs in the car.

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    BIC
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    Re: auto tranny from D to M on go and downshift causes 2 gear downshift

    The dealer has it and today said they ordered a new shifter. We'll see in a couple of days.

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    Awesome, please keep us posted!

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    Re: auto tranny from D to M on go and downshift causes 2 gear downshift

    Hey BIC,

    Glad to see you are working with the dealer to resolve your problem. Please let us know how it goes and feel free to reach out should you require additional assistance.

    Austin J.
    Cadillac Customer Care

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    Re: auto tranny from D to M on go and downshift causes 2 gear downshift

    When I go from D to M it always downshifts a couple of gears at highway speed, like from 6 to 4 (or is that 25 or 6 to 4...nevermind, that only happens in the Windy City). Moving right along, if I then almost immediately downshift again, it will only go to 3, not to 2 unless I have dropped revs/speed that would cause the algorithms to make this occur.

    Odds are, BIC, that there is something wrong here like you believe. Let us know if your new shifter help out, please.

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    BIC
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    Re: auto tranny from D to M on go and downshift causes 2 gear downshift

    Sorry for the delayed reply. First, they replaced the Transmission Control Module. Didn't fix it. Then replaced the Body Control Module, which they say did fix it. I don't know what either module does.

    I will say some things are different. Now, when I engage DSC, the M icon on the dash turns red; previously, was always white. I didn't even know that was supposed to change to red. It seems to downshift only one gear correctly (instead of the previous two) in the lower gears, from third or fourth, so no distress. But, when downshifting at low RPMs in fifth or sixth, it will drop two gears. But, those downshifts are smooth, so I'm guessing that's just a computer being smart. I guess I'm good, but wouldn't mind hearing from others that might do some testing to see if you can duplicate the results. Thanks.

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