Be careful on icy hills when you let off the throttle

Double your experience and the more you drive an auto like a standard in slippery conditions the more control you will have, especially slowing down or maintaining a slow speed.

 

Is it possible to program the computer to not have the harsh down shift??

 

Ive been driving on snow, and ice since the mid 60's, some vehicles with a manual tranny and some auto without an accident that was my fault. Imo, driving slower for those conditions is best when in traffic. As far as gears i let what i'm carrying, or towing dictate what gear is safest to drive in depending on speed, and road conditions.

 

Honest question... how does being in a lower gear help all? It will make every situation in slippery conditions worse. If you're trying to accelerate you'll have a higher likelihood of spinning the tires or if you're engine braking you'll have a better chance of locking the tires up. I can't see how that's beneficial.

 

with cruise engaged it will/should but, if you dont have the cruise set, it should not downshift, to maintain a speed. guessing that was the OP's issue as well. doesnt make sense it would down shift, if you are "coasting" down a hill. Ski

 

don't have a lead foot

 

I’ve said this for years. I definitely get the point they are trying to make when they say 4wd doesn’t stop any better, but it’s not technically true. When the front and rear diffs are locked together in 4wd the truck absolutely stops better.

 

Not really, with 4wd your vehicle will steer/handle better, but in no way will it stop any better than a 2wd if both vehicles are driven equal.

 

I have to disagree.
After driving in New England winters (NH) for 50 years, I know that the extra load on the 4wd drive train helps keep all wheels from locking up. In 2wd the fronts will lock up first and there goes your control.

 

One front and one rear will be rotating the same increasing traction. It helps maintain control during stopping on ice. Once while in and old Cordoba on snowy roads I was approaching a toll booth. So I took my foot off the gas and very lightly touched brakes. Immediately tranny upshifted-rear broke loose and I started to fishtail. Went to neutral and luckily regained control. Is OP absolutely sure the truck downshifted after creating the hill? I could see an up shift event causing the same symptoms. How does abs work differently on two front independently rotating wheels versus two driven wheels?

 

I drive in snowy/icy conditions on a weekly basis all through the winter. I have not had a problem with the shifting yet, but I have driven crap conditions most of my life, so know how to handle a vehicle in bad climate. The reason why things happen to vehicles in icy/winter climate is almost always operator error. I see it all the time. I know there are many exceptions and not saying that OP was the issue, but knowing your vehicle and the roads makes all the difference.

 

Your confusing traction with a vehicles handling. As far as braking the 4 wheels of a car should lock up at the same time, its the front wheels that then do the major amount of braking. If the fronts are locking up first, something isn't right.

 

A lot of good opinions and tips here, I agree with most of things stated. When driving on ice it's not good to break traction either accelerating or decelerating, stay off cruse control, give plenty of space in front of you, watch your rear view mirror for someone not paying attention to their distance, have good tires, 4 on a tread depth gage is NOT good in the winter, avoid sudden starts, stops and turns. Prepare for all these situations. Bad habits,equipment and inexperience cause most problems in winter, ice and wet conditions

 

Being in 4X4 would have probably meant all 4 wheels would have lost traction making the skid worse. You were driving too fast for the conditions. You may not have thought so, but if you were driving fast enough on ice for the truck to downshift you were driving too fast. You should have already manually downshifted to the proper gear before getting up that much speed.

 

@hvac9500Toyota & others.

FWIW my '21 TRD OR with auto will coast on downgrades without downshifting UNTIL I tap on the brakes - that's when it WILL 'self downshift.' The pitch and yaw sensors have an influence on how the transmission behaves on downgrades.

The major advantage to being in 4WD when braking is that you avoid the effect of the front wheels locking up before the rears. The constant power (while minimal) to the rear axle allows/causes the fronts to lock up first. I learned many years ago when driving an automatic transmission vehicle popping it into neutral when needing to decelerate offers much more control and avoids the front wheels locking up and losing directional (and braking) control.

Disagree. See above. If there is no power transmitted to ANY drive wheel, then one would expect braking to be appropriately distributed to all 4 wheels. But with an auto in Drive this is not what occurs, which is why the fronts will lock up first.
Been there too many times. With an auto, popping into neutral always provides both better braking and better control.

 

From what i've experienced all four brakes should begin to lock at the same time, its the fronts that have the most effect what you feel when in drive as they accomplish most of your braking. As far as improving on stopping I never tried braking in neutral with an auto, or manual so maybe you got something there....makes sense.

 

Although I agree that all four brakes should lock at the same time, every truck I have owned, full size, medium and small have all locked up the rear before the front. My guess is that it is done on purpose, so that all four brakes behave more evenly when there is a load on the truck bed.

 

This is why I live in Hawaii.

 

In my experience, how quickly an input (throttle, brake, steering) is executed will often determine if traction is lost or not, hence threshold braking; once you have exceeded the coefficient of friction, you'll start to slip. As you were heading downhill, you had even less weight on the rear wheels, when the truck downshifted, the trucks weight shifted forward, taking weight off the rear axle and lowering the friction of the surface. Tires are the other limiting factor in this equation as a good winter compound will have a higher coefficient of friction than all seasons. You could drive across black ice on bald tires and be fine, the difference being that with good tire compound, you may still have control when driver input is needed. Essentially, it comes down to weight and tire compound. Those things considered, a steady engine speed will be helpful in that you will not need as much braking input to slow down, and you will get more engine braking in 4WD without having to brake. Braking which will shift the weight onto the front axle on a decline and result in the rear sliding out.

 

If you're engine braking in 4wd, you will need less foot brake. More foot braking is likely to push your tires past their adhesion point and into a skid.