How and when should I use the power drive or winter drive button

Yes it does

Andrew, in automatic equipped vehicles with winter/wet mode selection, I believe it starts vehicle off in a higher gear to prevent wheel spin. Your manual should explain what winter/wet mode is.
Check the attached links,instruction and guides, Good luck
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Winter Mode Button Volvo Forums Volvo Enthusiasts Forum
http://www.volvoxc.com/forums/archive/index.php/t-4.html
http://www.edmunds.com/driving-tips/the-basics-of-driving-a-volvo-in-the-snow.html
What is the exact function of the Winter and Wet feature on the gear shift...

I believe the winter power button makes it so your truck starts in 2nd gear instead of 1st gear to reduce slipping and gain traction... It might do other things with 4 wheel drive. The whole point is to give you a better chance in the snow,

Those buttons are similar to traction control on some newer vehicles. The winter button causes less torque to be transfered to your tires all at once therefore reducing the chance of spinning. The power button allows all torque to be applied to you tires more for pulling a trailer or normal summer driving.

The winter drive button gears the transmission down so that it doesn’t spin when you take off from a dead stop in the snow and ice. It only activates by pressing and holding it when at a stop and then accelerating.

Power is for when you are hauling heavy loads. It holds a higher rpm before shifting to next gear giving you best hauling performance.

I believe '02 rodeo's have buttons for power mode and winter mode located between the shifter and the flip up console.You may have accidentally activated winter mode which cuts power to the drive wheels for driving in ice and snow.If so look on the instrument cluster and "winter mode" will be lit in green,simply push the button again to deactivate it while in PARK.Hope this helps ,good luck.

if im not mistaken the power button is used for towing the winter button is used for adverse wearher conditions such as snow -ice etc.(4wheel drive)

those buttons are for the transmission, power means that it will shift gears stronger with better take off and gear changes, winter is for slippery conditions it shifts smother and softer this way the truck wont loose control. some of these are automatic 4wheel drive the computer controls it, and some have a shifter on the floor with 2 wheeldrive then 4hi which is used in the snow and 4 low which should only be used to get unstuck or steep climb at low speeds.hope this helps.

Hello there.

The W/S mode button stands for Winter and Standard. Winter mode increases torque and thus adherence when starting. I believe that under normal conditions, standard mode is to be prefered as it improves acceleration and makes the ride more comfortable.

The ACR button inhibits the electronic drive assistance. This again might be necessary when driving under certain winter-conditions (snow, ice), but should normally be let active.

Power drive delays the shift points for upshift of the automatic transmission. It will degrade fuel economy, but you'll get more peppy performance.

Winter drive will only engage if the vehicle speed is below a certain threshold (I think 23 miles per hour) - and only if the vehicle is in Reverse, Neutral, or Drive. It causes the automatic transmission to start off in 3rd gear (rather than 1st gear). The purpose is to provide power, but not torque to the tires. In winter driving, torque increases the probablility of the tires spinning. The vehicle will seem to be VERY sluggish when winter driving is engaged - which is completely normal behaviour. It will automatically disengage when vehicle speed increases above the threshold.