Hi,
I was wondering what exactly does the dsc button do? When I'm driving in winter and turn off the dsc button it goes to rear wheel drive. And when it's on it engages awd. Is it ok in the summer to drive with it off? Does it hurt anything? I don't like it bothering me when I'm cornering hard, and my 18's seem to trip it off very easy.
Thanks I'm advance,
Mike

 

This is the relevant page of the owners manual.

 

Hi Mike,

I haven't checked the pdf as I am fed up uploading those applications.

To my knowledge the DSC is designed as a "Dynamic Stability Control" and it is a safety feature I had on a previous X-Type.

It is utilised to reduce/release movement on your wheels to discourage wheelspin and slide in adverse weather conditions and it is very good.

In a car park full of snow (without obstacle or hazards), it may be fun to test the system with it on then off.

You will then really appreciate the difference.

I am actually surprised that your system switches between the 2 and 4 wheel drive so I am sure you have a newer model than any of my cars?

I am not sure of your terminology "trip it off", but if in doubt I would engage the DSC in bad weather and I am sure you can do without it in fine dry conditions.

Using DSC will increase fuel consumption but in hazardous areas I would use it without doubt.

I hope this helps and enjoy your drive Mike. Regards, Stu

 

Fear not, the car remains in AWD at all times - it is non selectable by DSC!

 

Hmm, what about the later models that have no viscous coupling? In them the redirecting of torque is handled by the DSC via ABS, so if you turn off DSC, won't your center differential start acting truly "open" again? Or is that functionality not turn-offable?

 

I've posted this Jaguar training document before, but it's probably the best explanation of what's going on, with or without VC or DSC

 

Oh, I've read that. It didn't really answer my question, I know what the DSC does, but I don't know whether when you turn it off, it turns off the whole DSC including the "pseudo-VC" or just the features a DSC- and VC-equipped car (like the early sport-models?) would have in the DSC.

 

It is my understanding that the DSC simply engages the brakes to the slipping wheel(s). By doing this, the wheel is slowed down and the power is then transferred to the non-slipping wheels. In short, because you have an open differential for the front wheels, an open differential for the rear wheels, and an open differential in the transfer case, without DSC (or with it turned off), when one wheel looses traction, it will take all the power (some will still make it to the opposite end of the car as the transfer case is not truely open differential). So, on dry pavement, the likelihood of a wheel slipping is very minimal and therefore the need for the DSC being on is not needed. But, you start getting into rainy weather or snow/ice, the amount of available traction is reduced and the likelihood of a slipping wheel is higher. This is when DSC would be advantageous as it will keep the 4 wheels all moving at about the same speed.

 

Hi Everyone,
I have tested my DSC button last winter. My driveway is up a hill. I had DSC on and then the car spun tires and gripped and went. I then did it again, turned DSC off, and it just spun the rear tires and would not move an inch...

 

Thanks for the explanation Thermo & for the verification of the theory in practice JaguarXKR. I was mostly familiar with the drivetrain in theory but not that well aware of the DSC. I actually recall once explaining the VC-less drivetrain to someone by comparing it to an electric circuit, the idea being that the power will always take the easiest way out.

I see now that your (JaguarXKR) signature states a 07 X-Type, so indeed it has no viscous coupling and will mostly spun the rear wheels without DSC in such conditions. By the way, I've heard that when DSC is disabled it is possible to force some power to the front wheels by lightly applying the handbrake. There are some rare unfortunate X-Types that have no VC or DSC, so their AWD performance is seriously hampered since they have 4 "traction-critical" wheels.

 

Mike, you have actually answered your query in that statement and Thermo puts it perfectly.

My answer as usual goes around the bush and back, somewhat but the DSC works on your vehicle and that is the main point of the whole issue.

Now where's that snow, aha in Bonnie Scotland it won't be long, ARRRRR!

Regards, Stu

 

Aonsaithya, by applying the handbrake, you are effectively doing what the DSC system is. You are putting more drag on the rear wheels (which have more power applied to them) and letting the front tires apply more (relatively speaking) power to the ground. In this case, the hand brake is "eating up" some of the power making the tractive effort favor the front wheels as it relates to the power making it to the ground.

 

Indeed, and thus the DSC also causes some power loss when in operaton, unlike the viscous coupling if I'm not mistaken, however that difference is likely immeasurable.

 

I am actually in the upper peninsula of Michigan for school right now. It has snowed about two inches a night the last few nights...so don't feel to bad about getting snow already

 

I have a 03 X type and a short uphill drive way,at one time I can home to a snowy driveway(about 8/9 inches) I got about 1/2 way up in AWD and wouldn't go any further,after a few tries I turned off DSC and floored it, snow spit from all tires as I cranked the wheel from side to side and I climbed up successfully. With the DSC activated the tires wouldn't spin and lights flashed and ABS was activating( the noise was loud) but with limited RPM (power) I couldn't move. Other than that you can't get it to spin or even slide with DSC activated, I love it! Stopping is a different story because without traction(road adhesion) ABS can only do so much and the cars momentum will overpower the adhesion and you will slide until it is equal or you hit a solid object.Physics is wonderful BUT it's predictable.

 

The significant power loss is not because the DSC brakes a wheel or two, as that lost power is transferred to the other turning wheels as the diffs operate. However, another aspect of DSC is that when it cuts in it also reduces the fuel to the engine to reduce overall torque output as it tries to rein in what it percieves as driver impetuosity!!