O/D Button on the shift nob? What does it do?

[slowmotionzx]

I recently found out that my shift nob has a button. When i press it the dash says O/D OFF. (i drive an automatic btw) What does it do? I'm guessing OD stands for overdrive?? Will i get better gas mileage by having O/D OFF?

[dee_tymz_sl]

I recently found out that my shift nob has a button. When i press it the dash says O/D OFF. (i drive an automatic btw) What does it do? I'm guessing OD stands for overdrive?? Will i get better gas mileage by having O/D OFF?

When you press the OD button and you see it light up on the dash what happens is that it locks the transmission in a lower gear; short of like downshifting with a manual. However keeping it there actually lowers gas mileage, and yes it stands for overdrive...

[Mubbly]

I turn it off (press it so the light shows on the dash) when going up steep grades for better hill acceleration. Probably not a good idea to use it at high speeds.. for fuel economy purposes.

EDIT: BAM!

08 Owner's Manual

"OFF: For driving up and down long slopes where engine braking is necessary, push the Overdrive switch once. The indicator light in the instrument panel will illuminate. When cruising at a low speed or climbing a gentle slope, you may feel uncomfortable shift shocks as the transmission shifts into and out of Overdrive repeatedly.

In this case, push the Overdrive switch to turn the Overdrive off. The indicator light in the instrument panel will illuminate. When driving conditions change, depress the Overdrive switch to turn the Overdrive on. The indicator light in the instrument panel will turn off.

Remember not to drive at high speeds for extended periods of time with the Overdrive off. This reduces fuel economy."

Also..

"Accelerator downshift in D position —

For passing or hill climbing, depress the acceleratorpedal to the floor. This shifts the transmissiondown into a lower gear, depending on thevehicle speed." Thoughts?

I'll have to try this. Seems kinda freaky to push it to the floor. This might explain the A/T's terrible hill performance. Worth a try, I guess.

Modified by Mubbly at 4:55 PM 6/15/2009
Modified by Mubbly at 4:56 PM 6/15/2009

[bladesbravo]

I duno if its because i have CVT, but pushing it to the floor dosn't really help me to much with passing.

[MinisterofDOOM]

Overdrive is just top gear. Hitting the OD off button limits the trans to the first 3 gears and locks out 4th, which is overdrive.

It does the same thing as a "3" position would do on the shifter. The reason it is called overdrive is that the wheels are "over driven" meaning the ratio of rotation is greater in favor of the wheels. Normal the motor turns multiple times for each rotation of the tires. In overdrive, it's the opposite. The purpose of this is to allow you to cruise at low RPM at high speeds. But the gearing down reduces power, so turning OD off in hilly terrain or when driving a heftily loaded car will leave you with more convenient power.

As for the accelerator to the floor deal, that's totally normal and something found on all automatic cars. There's a "WOT" (wide-open throttle) sensor that detects full throttle and signals the transmission to downshift if possible for max power. Basically it's just a simple way to trigger a downshift for power when you need it.Actually, you can go even deeper than just "floor it" if you really want to learn to "manually" shift your auto. Automatic transmissions have "maps" of speed versus throttle which they use to decide which gear to be in and when to shift up or down. You can modulate throttle to cause the car to shift at different times. Can be used for up- or downshifting depending on conditions. Just have to get a feel for the particular car/transmission to know exactly what inputs cause what results. Once you get to know your car, you can essentially shift with the accelerator pedal.

[Shad0wXCalibur]

I duno if its because i have CVT, but pushing it to the floor dosn't really help me to much with passing.

You serious? When I push the gas, my CVT sticks the RPMs around 5,000 and makes it fly around someone.

[frankoV]

You serious? When I push the gas, my CVT sticks the RPMs around 5,000 and makes it fly around someone.

ditto . . . the sewing machine they call an engine has a bit of power to it and does the job

[eeshazor]

I know I'm super late on this.. but are we all suggesting that the overdrive function should be left ON while I'm driving at high speeds? When overdrive is on, the car is much noisier.. which I would assume means my engine is working harder? So why would that help my fuel economy? The only time I use overdrive is when I AM going uphill; it stops me from rolling back (i.e. On La Cienega making a right turn onto Sunset Blvd. in Hollywood, CA... ridiculous hill!!)

[Promise Land]

are we all suggesting that the overdrive function should be left ON while I'm driving at high speeds?

At high speeds, OD will lower your engine speed and use less gasoline. It should be quieter too. Around town, you may or may not use your OD a lot if you don't drive fast enough to get to OD or a 4th gear.

[eeshazor]

Ohhhh, O/D is default ON, I was getting it the opposite impression. Silly me haha.

[Shad0wXCalibur]

If you do a lot of low speed city driving, it's a good practice to turn OD off to keep the transmission from shifting back and forth from 3rd and 4th which starts heating up the transmission big time.

[MinisterofDOOM]

I know I'm super late on this.. but are we all suggesting that the overdrive function should be left ON while I'm driving at high speeds? When overdrive is on, the car is much noisier.. which I would assume means my engine is working harder? So why would that help my fuel economy? The only time I use overdrive is when I AM going uphill; it stops me from rolling back (i.e. On La Cienega making a right turn onto Sunset Blvd. in Hollywood, CA... ridiculous hill!!)

Overdrive is simply the highest gear on most modern transmissions.
Don't think of overdrive as overdrive. Think of it as a gear, with a number, which it really is.
In a manual transmission, you have, say, 5 speeds. 1, 2, 3, 4, and 5. 5 is overdrive, but it's not usually called that. Just like any other gear, you shift into 5th gear as needed. Just pretend the term "overdrive" doesn't exist. On Nissan's 6 speed manuals, 5th AND 6th are overdrive, with 6th more overdriven than 5th.

All that applies to automatics, too, except you USUALLY don't do the shifting. But you CAN manually shift, and that's what the OD button is for. It's just the top-gear shifter position, even if it's a button instead of a shifter position. And sometimes overdrive actually IS a shifter position. You won't find an Overdrive button, switch, or label of any kind in my Q45 or LS8 (both automatics). The Q's shifter has positions for 1, 2, 3, and 4. 4 is overdrive. The LS8 has positions for 1 through 5, and 5 is overdrive.

The purpose of multiple gears is to provide a way to keep engine speed (RPM) from maxing out and limiting car speed. If you only had 1st gear, you couldn't go more than 20-something mph and even then you'd be working the engine hard and using lots of gas. So you add a gear. Now you can go a little faster without hitting redline. Add another gear and you can go faster still.

So, yes, you should be using overdrive at high speeds. That is the sole purpose of overdrive, the only reason it exists.

To address your points specifically:

The only time I use overdrive is when I AM going uphill; it stops me from rolling back

That's simply not possible. Regardless of the position of the Overdrive switch, overdrive is only ever in use when the car is in motion and travelling faster than ~35 (maybe higher for the Versa) at a constant rate (cruising) with no real acceleration load on the car. If you try to accelerate, increase throttle, or start going up even a slight incline, the transmission will shift out of overdrive for power. When stopped, the car shifts into 1st gear. Overdrive is 4th gear. It's not in use yet.

So why would that help my fuel economy?

Every time a piston fires, it uses fuel. The faster your engine is turning (RPMs) the more times per second each piston is firing. Higher engine RPMs means using more fuel. The best way to improve fuel economy is to keep RPMs as low as possible. Going back to what I said above about why cars have more than one gear in the first place, Overdrive (and every gear) is simply there to allow you to achieve greater vehicle speed without having to drastically (and for long periods of time) increase engine speed. The faster you go, the higher the gear you need to keep RPMs low. Low RPMs = less fuel consumed. The right gear to maintain your current speed is what it's all about. Finding the right mix of enough power and low RPMs. Too high a gear and the car isn't making enough power. Too low a gear and you're revving high and overworking the engine and wasting fuel.

Which brings me to my next point:

When overdrive is on, the car is much noisier.. which I would assume means my engine is working harder?

Your engine is working LESS hard, actually. But, if the car really is significantly noisier with overdrive on, you might have a problem. Just keep in mind that Overdrive ONLY APPLIES WHEN THE CAR IS ACTUALLY USING TOP GEAR. So merely leaving the O/D switch "on" doesn't affect anything at all unless you're cruising at a steady 35+. Which means the difference in noise may very well stem from something else entirely.

Really, there are only a handful of times you should ever really need to disable overdrive:
--When driving using Cruise Control on hilly terrain (to keep the transmission from "hunting" and shifting back and forth between 3rd and 4th excessively)
--When you anticipate a need to pass on the highway and want temporarily increased passing power.
--When using engine speed to slow the car (engine braking) descending a hill.
--When towing (which probably isn't an issue for most Versa owners). This goes back to the whole balancing power with efficiency thing. Towing with overdrive enabled can be very stressful on a transmission.
Aside from those, unless you're driving aggressively, the car will use or not use overdrive as it sees the need, and having that extra gear option available is only helping.

I wish cars and their manuals would do a better job of explaining how (and why) things work instead of just putting nebulous-sounding buttons and labels on things. The more people understand about what does what on their car, the better off the are. Oversimplifying things just leaves people in need of answers.

[KimberKenobi]

You serious? When I push the gas, my CVT sticks the RPMs around 5,000 and makes it fly around someone.

ditto . . . the sewing machine they call an engine has a bit of power to it and does the job

For Me too...

(sewing machine... rofl!)

[eeshazor]

Lol ministerofdoom ... I said that I had it backwards :P As in,
i turn overdrive OFF when I'm on a steep hill which keeps me from rolling back,
and when I have overdrive OFF, thats when the engine gets noisy. I had just gotten it backwards and thought the whole time that the default of overdrive was 'off.'
But thanks for explaining how it works, I understand now :]

[MinisterofDOOM]

Lol ministerofdoom ... I said that I had it backwards :P As in,
i turn overdrive OFF when I'm on a steep hill which keeps me from rolling back,
and when I have overdrive OFF, thats when the engine gets noisy. I had just gotten it backwards and thought the whole time that the default of overdrive was 'off.'
But thanks for explaining how it works, I understand now :]

Ahh, I missed that post.

I hope I didn't make you feel like I thought you were dumb. I just notice that, especially with economy cars, there are a lot of non-car-people owners who don't ever feel the need to learn this stuff, which is too bad considering how useful even basic info can be. So it's nice to have it out there. Maybe someone will search for "what does O/D button do" and find that info useful... For example, my mom's certainly not clueless when it comes to cars but when she drives my Lincoln she still always asks me "Should I put it in D5 or D4?" because she's so used to her Maxima's single Drive position.

And of course the CVT adds even MORE confusing by using similar terms and faking "gears" even though there aren't any. Automakers really aren't doing any favors by treating customers as though they're too dumb to understand basic concepts.