4WD crash course, er I mean tutorial..

[Master Yoder]

I have never owned a SUV or truck with 4WD so I am not very familiar with it. I have a 2002 SR5 Sport if that makes any difference.

I read on a web site that you can switch to 4WD as long as you are under 60 mph, is that safe to do or is it better to stop first if you are able to?

What are the main differences between low and high gear 4WD? I would assume that low is when you are stuck deeper in snow or mud and it is harder to get out but are there certain speeds that you should be in low gear and certain speeds you should be in high gear?

If the roads are snowed in do you drive in 2WD whenever you can and only go to 4WD if you start spinning or is it safe to drive in 4WD long distances when you are in a situation that "could" get slippery etc. like the roads have a lot of snow on them but you can drive in 2WD for the most part.

How do I tell if I have differential locking, what does that do exactly? I have a button that light up a VSC light when I am in 4WD mode but I don't really know what that does actually other than it is Vehicle Skid Control.

One other thing I noticed is when I move the stick from high to low it seems pretty tight, is that normal? i guess it prevents you from accidentally going to low while you are driving.

Sorry for all the green questions, I have been wanting to get a good SUV for a long time so i am glad I was finally able to.

 

[pat161]

I will ignore the VSC and locked as I answered those in your other post. Lo gear is an extra reduction in your transfer case for really tough conditions. I have been stuck in snow pretty bad and never needed lo to get out. It basically is used for crawling off road, if you switch to lo you will see that your rpm will be much higher at any given speed, thus you can put along at 5mph and still be pushing 3k rpm and have good power. I believe the lo reduction in the 3rd gen is 2.3 to 1 or close to that, while 4hi is 1-1. The owners manual says you should stop and switch to N before going into 4lo.
With your 02 and it's full time 4wd ability you can be in 4wd anytime you want, so if there is snow on the back roads and none on the main roads you can put it in 4wd and forget it, on my 00 w/o the center diff I would often not use 4wd because I hated switching back every time I hit a main road. As for the shift on the fly into 4hi, this is no problem at all, I think the mph is 50 and not 60, but it is ok to shift into 4wd while driving. If you are lacking traction already it won't instantly go into 4wd, so if you are 1/2 way up a hill spinning tires and you hit 4wd it will not switch in until you let off the gas, so it may be better to be in 4wd before you get stuck, though w/ my 00 I never had a problem getting moving 1/2 way up a hill.

 

[boston_kevin]

couple of things to keep in mind about 4wd...

1) It helps you to get started faster in slippery conditions, but it won't help you stop. The braking system is the same no matter how many wheels are driving.

2) 4WD HI is for normal slippery conditions. Basically any time you need additional traction, use 4WD HI. I am not sure if the 3rd gen allows for 4HI on drive pavement.

3) 4WD Lo is for conditions where you need the maximum amount of torque applied to the ground (rock crawling, creeping up slippery surfaces, etc). Speed in 4Lo cannot exceed 30 mph (and that is maxing out the RPMs in top gear) and is usually reserved for speeds under 10 mph. 4Lo always requires the vehicle to be completely stopped (and the drive train disengaged in some vehicles) to engage. I've used it on a slippery boat ramp and pulling people out of snow banks.

4) Locking the diffs requires 4WD and conditions where the wheels on each side of the axle can move at the same speed (i.e. not around tight turns on dry roads). Once you engage the diff lock, you will disengage another sensor on the truck for the VSC so this safety system is now disabled until you unlock the diffs. Basically, this is an off-road feature.

 

[pat161]

He only has a locking center diff, his front and rear axles are open open no matter what button is pushed.