Does my 2002 XC have DST?

[PierreC]

This may be an unusual question but how do I determine whether my 2002 model has STC (Stability and Traction Control)?

According to the owner's manual. there will be a button (switch) to switch off/on either STC or DSTC, but my wagon does not have this button. Am I therefore correct to assume that I don't have STC or is there a definitive way to determine this from the VIN?

PS Reason for asking is that I have a hissing sound in the footwell when releasing the brake pedal, and an occasional very hard brake pedal (loss of bosster pressure) - i.e. a failing / failed booster that needs to be replaced. Replacement booster parts all differentiate either "with" or "without" stability control.

[stupidloose]

I don't know much about reading your VIN# to find out; But I know Ive seen in the IPD catalog both boosters for sale. The booster equipped with DSTC has an electrical connector on the face of the booster to the left of the master cylinder; The others don't. http://www.ipdusa.com/products/8567/113495-brake-booster-1999-2009-p2-s60-80-v70-xc70-with-dstc

[Willy]

Only DSTC equiped MY2002 XC's have the button. If there is no button, the car still has STC.
There are no XC's without STC, in case of a DSTC car the button only disables the "D" part.
Willy

[PierreC]

Thanks stupidloose & Willy for the info ...

[PierreC]

... so this one will be OK?

http://shop.carpartsone.com/buy.php?make_text=volvo&model_text=xc70&ml=xc70-4wdt-004&year=2002&part_name=brake_booster&brand_name=ate&make_code=VO

Pierre

[Skater]

Only DSTC equiped MY2002 XC's have the button. If there is no button, the car still has STC.
There are no XC's without STC, in case of a DSTC car the button only disables the "D" part.
Willy
I disagree. My 2006 has no button, and I can spin the wheels indefinitely on snow. Unless I am wrong, the stability and traction control should stop the wheels from spinning, correct? My all wheel drive kicks in, and I get the flashing triangle slipping symbol on my dash, but my wheels continue to spin.

[Ars Gladius]

I disagree. My 2006 has no button, and I can spin the wheels indefinitely on snow. Unless I am wrong, the stability and traction control should stop the wheels from spinning, correct? My all wheel drive kicks in, and I get the flashing triangle slipping symbol on my dash, but my wheels continue to spin.

STC will not stop wheel spin, it attempts to limit it, but only up to a certain point. Just like DSTC will not stop a spinout if you have exceed it's ability to intervene.



STC


• 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 traction function works at lower speeds, up to 25 mph, 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 minimizes wheel spin and helps bring 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 around, DSTC gently returns it to the right line. Applying the brakes on one or more wheels does this.

• 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 behavior of the car.

• The DSTC processor receives the signals and compares the actual behavior of the car with the desired behavior. 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 partially compensate for the driver's 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. 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 has been added.

[budrichard]

There are no 2002 XC70's with DSTC. It was only an option when the electronic Haldex was introduced in 2003. How do I know, because I specifically waited until 2003 to be able to order DSTC, of course my Salesman wanting to sell me the vehicle on the lot, insisted it wasn't needed. My 2003 XC70 with DSTC was the first in the USA.
If you don't have a DSTC button or if you can't switch DSTC ON or OFF by the information stalk on later models, you don't have DSTC.
The only reason to switch OFF DSTC is if off road and/or in deep snow/mud where you want the wheels to spin and not stop because of Traction control. Try it with a DSTC vehicle in deep snow. Get the vehicle bogged down and then switch OFF DSTC, you will immediately have more grip which of course is dependent on your tires.-Dick

[Ocean Racer]

This may be an unusual question but how do I determine whether my 2002 model ...

PS Reason for asking is that I have a hissing sound in the footwell when releasing the brake pedal, and an occasional very hard brake pedal (loss of bosster pressure) - i.e. a failing / failed booster that needs to be replaced. Replacement booster parts all differentiate either "with" or "without" stability control.

Hey mine does the exact same thing! I'm currently trying to find the cause.

[Ocean Racer]

For the record, I can spin the wheels all day wet and dry and there is a flashing orange dtsc or stc on the dash. It does retard power to the wheels and you feel it big time when it turns off under load.

[Ars Gladius]

This may be an unusual question but how do I determine whether my 2002 model ...

PS Reason for asking is that I have a hissing sound in the footwell when releasing the brake pedal, and an occasional very hard brake pedal (loss of bosster pressure) - i.e. a failing / failed booster that needs to be replaced. Replacement booster parts all differentiate either "with" or "without" stability control.

Hey mine does the exact same thing! I'm currently trying to find the cause.

If it is not the brake booster causing the hissing, have a look at this thread (http://www.volvoxc.com/forums/showthread.php?t=13675&highlight=hissing).




As for which booster to get, if you car does not have a traction button on the console or a button on one of the control stalks (later years) then you do not have DSTC.


The other slightly harder way to find out is to look at your existing booster. Cars with DSTC will have a wire harness that connects to the booster. Cars with the standard STC do not.

DSTC:
http://www.ipdusa.com/uploads/images_products_slideshow/fullsize_6764.jpg

STC:
http://www.ipdusa.com/uploads/images_products_slideshow/fullsize_6763.jpg

[mhrir]

As was said earlier, 2002 and earlier XC models were not offered with DSTC as an option. When the switch to the electronically controlled Haldex AWD was introduced DSTC became available. Further trivia: Two wheel drive models did offer DSTC in 2002; 2.4T as an option and T5 as standard .