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D1 and D2

We have a Toyota Camry 2000 LE automatic. I use N D R but my husband in addition uses D1 and D2 to navigate hills. Is this necessary? What are D1 and D2 for?

Thanks

D1 and D2 are unnecessary but harmless. All they do is prevent the transmission from shifting into any higher a gear than the one the shifter designates. Put it in D2 and it’ll not shift above second gear. Put it on D1 and it will not shift above 1st gear. The ECU will prevent the engine from overreving. However, there may be additional wear on the drivetrain.

i’ve learned that with my car, which uses a Camry drivetrain, if I leav it in “D” I cannot use the engine compression to slow the car, but by shifting into “3” I can. In “D” the engine drops immediately to an idle position, in “3” the engine revs drops slowly and I can feel the compression helping. I can also feel the vacuum on the fromt of the booster diaphragm helping, as when the gas is lifted in a car in gear the vacuum spikes in the cylinders. Is this what hubby is actually doing?

If you’re going down a long steep hill, you should use a lower gear so that you’re not overusing (and overheating) your brakes, which is dangerous. D2 may be the gear you’d end up using for this.

If you need more power to merge or pass, you might choose to downshift using the shift lever instead of just pushing down on the gas pedal until the transmission decides to downshift on its own.

Modern vehicles(inc 2000’s) automatic’s are fine with N D R. D1 and D2 are there for historic reasons mostly. The situation where they are needed likely is about 0.1% of drive time of a vehicle.

I actually use “3” often. I drive a road on the way to and from work that constantly speeds up and slows down, and rolls up & down. I drive it for about 7 miles. I find it easier to use the engine compression and just control the speed variations with my gas pedal rather than constantly using my brakes.

Same…“D1 and D2 are unnecessary but harmless.” raj…"D1 and D2 are there for historic reasons mostly. "

Sorry guys…but I totally disagree. These shift choices are there for a reason and if the driver chooses not to use them according to the manual, it’s his loss. The modern automatic can handle constant shifting as the situation occurs and the car performs better overall when doing so manually when appropriate.

I frequently drop the shifter in my auto down a gear (or even two) in hilly in town areas towing (and on my dirt mountain road) to help keep the speed in check and give the “brakes a break”. It is NO more wearing on the auto to use it as engine braking as many do now automatically, then in a manual which we all used to do by limiting up shifts in town by not even shifting into 4th or 5th gear. What is the difference between that and not Using one of the optional gear restrictions on an auto.

I submit that if you DON’T use them, you are driving in a less then efficient way, just as you would trying to use 5th gear in a manual in town. I would argue that there are in town situations where not using them would find you in the wrong gear most of the time. The auto responds to load, it does not automatically sense that keeping your speed in check using both the motor and brakes together is safer. That’s the driver’s job and one of the reasons for D1 and D2. Hubby may be doing it RIGHT as we may be debating this by degree.

Maybe I am just spoiled by a great automatic in my 2007 Acura MDX. It shifts/downshifts appropriately and responds to your foot. This is on steep gravel roads, steep highway grades and very light off road.

I never touch the shifter.

Never had the luxury of driving a great car with intelligent shifting. Just speaking from a “slug” owner point of view.

I have an 3 speed automatic in my Ford truck with the D1 & D2 optional positions on the selector. I use them both when going downhill, using the engine to brake and slow the car a bit without needing to apply the brakes. It’s easiler to control the car with engine braking than applying the brakes. D1 applies more engine braking than D2, so which one I use depends on how steep the hill is and how fast I want to go.

Also, when I’m pulling a stump out or something, with a rope tied to the hitch say, I use D1 so it stays in low gear.

If I didn’t have D1 and D2, I can’t say I’d lose any sleep about it. But sometimes they are useful.

Thanks for all the responses. Hubby uses D2 to go up and down hills. But I only use D to drive forward. Isn’t it not good to use the engine to slow the car instead of the brakes?

Thanks.

Just the opposite is true. Motors are designed to provide some engine braking and transmissions are designed to provide the control for it. The truth is, you use both and hubby may be OK. Using D2 going up is redundant as the trans will use the appropriate gear. Going down isn’t bad in D2 if he is doing it to keep speed under control. The manual will explain the appropriate use of each position.

ssfmas wrote:
Isn’t it not good to use the engine to slow the car instead of the brakes?

If the brakes overheat, you’ll have no brakes. That will be not good for the car and not good for you!

Again cars are designed to run nearly exclusively in D. The lower gears are there for extreme cases where the transmission grade logic is lacking or elongated downhills.

For example Mt Washington Auto road use a lower gear going down. Or a long mountain road. However you will notice signs about lower gears etc. Car brakes are well designed in a Camry to handle it slowing down.

You may notice in brand new cars D1 or D2 is completely gone. Honda does this as do other makers.

Dag, you’ve left me confused. You state that you disagree with my comment that using D1 and D2 is unnecessary but harmless, then go on to state (correctly) that modern transmissions can handle constant shofting as the sitiuation occurs, then proceeding to state that you use the lower positions to better regulate your speed, as I stated in my post that I also do.

Your statements suggest that you consider the use of “D” harmless, but also consider the use of the lower positions harmless. It would seem that we’re in agreement. We both consider leaving it in “D” harmelss and both personally use the lower positions for better control under certain circumstances.