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Thread: What is DSTC? And how do you guys use the W(inter) mode

  1. #1
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    Default What is DSTC? And how do you guys use the W(inter) mode

    Hi. What is DSTC, and how do I shut it off? Or should I shut it off? I saw another post about shutting it off during winter months?

    Secondly, when and how do you guys use the W(inter) mode on the transmission box.

    Thanks.

  2. #2
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    According to Volvo:

    STC
    Stability and Traction Control (STC) can be described as a combination of two existing Volvo systems, the low-speed, brake-activating TRACS system in the S70/V70/C70 models and the speed-independent, torque-limiting DSA system in the S40 and V40.

    STC is designed to prevent the driving wheels from spinning when starting and accelerating, as well as counteracting wheel spin if the driving wheels hit slippery patches when driving.

    The system improves tyre grip on slippery surfaces and provides the optimum combination of traction and side stability which in turn enhances the high level of active safety.

    The traction function works at lower speeds, up to 40 kph, by transferring the engine power to the wheel with the best grip from the one with the least grip. This is done using the ABS sensors and the brake system.

    The stability function reduces engine torque, by cutting down on the fuel supply, if one of the driving wheels starts to lose its grip on the road, both during acceleration and when driving on a slippery road. This minimises wheel spin and brings the car back to full stability.

    The system reacts and is activated within milliseconds and driving characteristics are never affected. An indicator lamp on the dashboard flashes if and when STC is engaged.


    DSTC
    Dynamic Stability and Traction Control (DSTC) is an even more sophisticated stability system to improve active safety by also intervening and counteracting any tendency to skid.

    If the car makes a sudden movement and loses its directional line, or enters a corner too fast and the rear end starts to turn the car inwards, DSTC gently returns it to the right line. This is done by applying the brakes on one or more wheels.

    DSTC works through the ABS system, which has been further developed.

    A number of yaw angle sensors monitor the rotational speed of all four wheels, the steering wheel angle and the directional behaviour of the car.

    The DSTC processor receives the signals and compares the actual behaviour of the car with the desired behaviour. Any deviation from the norm, such as the rear wheels starting to break away, and the system intervenes and makes corrections, activating the brakes on the wheel that will bring the car back in line. If necessary, the system also reduces engine torque, like STC.

    In a way, it would be true to say that DSTC is able to compensate for the driverís mistakes up to a certain point, as it counteracts and prevents skidding when the driver has already started to lose control.

    The system is particularly effective if the driver has to brake hard and steer away at the same time, like the well-known elk test. The system counteracts any tendencies to skid and returns the car to its original course.

    DSTC works through the ABS system which has been further developed to incorporate this system. In addition to more relief valves and a more powerful microprocessor, a brake reinforcement unit with electronic activation, sensors for side acceleration, yaw rate and steering wheel angle have been added.

    DSTC can only partly be disabled. I can't help you with "W" mode, it is not applicable to manual transmissions
    Willy
    144 GL (1974)--->244 GL (1982)--->940 GLE 2.3i (1992)--->XC70 2.5T (2004)

  3. #3
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    Quote Originally Posted by chinapat View Post
    Hi. What is DSTC, and how do I shut it off? Or should I shut it off? I saw another post about shutting it off during winter months?

    Secondly, when and how do you guys use the W(inter) mode on the transmission box.

    Thanks.
    I always use the W feature in wet and snowy conditions. It's most noticeable when moving off from a stopped situation as 2nd gear is used to move the car and help the car maintain traction.

    The DTSC is something I simply rely on as being there to help me with nasty/difficult road surface conditions safely. I do not think about it at all anymore.
    Regards -- Barry Sharp
    ==============
    Current: MY2012 XC70 T6/Twi Bronze/Espresso Brown/Polestar/Platinum/BLIS/Tech/ABL/Scuff Plates/Front&Rear cameras
    Traded 2011 C30 R-Design
    Son's '01 S60 2.3L T5,Maya Gold,96Kmi
    Son's '03 XC70 Platinum Green (OSD)
    Daughter#1 2011 XC60
    Daughter#2 2010 XC90
    SOLD '86 745 GLE 6-Cyl-Turbo Diesel,Graphite,255Kmi
    SOLD '03 XC70 to my son
    SOLD '03 XC70, '04 S60R, '07 S60R

  4. #4
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    I don't think it's advisable to ever turn off your DTSC unless you want to drive like you stole it.

    The W mode is to be only used in extreme weather conditions as its purpose is for nasty road conditions (heavy snow and ice, or heavy rain). Since my MY04 is already equipped with DTSC, the W function is a moot point. Besides, I get to have more fun with it in the winter time.
    Ed (Forkster) Reddy - Blue MY04 XC70 with Volvo Moose stickers

  5. #5
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    There is a buttom to disengage DSTC for a reason. In dry or wet conditions DSTC helps prevent losing control. However in snow you will normally experience some wheel spin (before AWD takes over) and lateral sliding. Previous threads have indicated situations when in snowy conditions with DSTC engaged, the vehicle will gradually come to a complete stop. Once DSTC is disengaged the driver was able to continue with the Haldex AWD doing its job.
    2006 XC70 Ruby Red, mfg 03/06
    2005 S80 Ash Gold, mfg 11/04

  6. #6
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    TG... you wrote...

    "There is a buttom to disengage DSTC for a reason. "

    Where is this button? I can't find it on my 07.

  7. #7
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    The button is on the center console, bottom row.
    If there is no such button, I think the car may have no DSTC.
    Willy
    144 GL (1974)--->244 GL (1982)--->940 GLE 2.3i (1992)--->XC70 2.5T (2004)

  8. #8
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    Quote Originally Posted by Willy View Post
    The button is on the center console, bottom row.
    If there is no such button, I think the car may have no DSTC.
    Willy
    DSTC is standard on 07's. twist the info knob at the end of the turn signal until you get to DSTC then you can tap the reset button to reduce.

    READ YOUR OWNER'S MANUAL

  9. #9
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    To succintly answer your questions:
    1. You cannot turn OFF the Dynamic Stability feature but only disable the 'Traction Control' feature.
    2. Never use the W Mode, it is not needed.
    The W Mode is absolutely useless and I never use it on my 1999XC or 2003 XC with DSTC. On the older mechaincal Haldex systems, the use of W Mode in deep snow will stall your vehicle as it starts you out in third gear with very little power. In a XC with DSTC, in deep snow do not use the W Mode and Turn OFF DSTC which does not disable the 'Yaw Control' feature but only turns OFF the 'Traction Control' allowing power to be constanly transfrerred to the wheels whether spinning or not. With 'Traction Control' ON, if the wheels spin in deep snow, the brakes are applied and you will get stuck.
    On road, i leave DSTC ON and W OFF in up to 6-8" of snow. Off road, i always turn DSTC OFF to disable 'Traction Control'.
    BTW if anyone doesn't believe me, go ahead and try using either or both the W Mode and 'Traction control' in deep snow.-Dick
    '11 XC70 Silver/Off Black-Hers
    '03 XC70 Silver/Charcoal-His
    '99 XC70 Silver/Charcoal
    '87 740GLE Junk Yard@287K miles

  10. #10
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    Agreed but I've said this before and no one wants to listen.
    NEVER use the W mode, not necessary and can possibly hurt the trans if used too much.
    Learn how to drive in snow, this is a much better idea!

    (Let's not get into another discussion here why, that's been covered before)

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