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O/D button on clutch?

A

AmberClad

Diamond Member
When I was starting up the car this morning (in the dark), I accidentally hit a button under the normal clutch-unlock button. An orange light indicator on the dash came on that read "O/D OFF". I've owned this car for years and this is the first time I've noticed that little button. Anyways, I hit the button again immediately and the indicator turned off and I went on my way.

What is "O/D"? And what would have happened if I had driven with it "Off" 😕?
 
Originally posted by: AmberClad
When I was starting up the car this morning (in the dark), I accidentally hit a button under the normal clutch-unlock button. An orange light indicator on the dash came on that read "O/D OFF". I've owned this car for years and this is the first time I've noticed that little button. Anyways, I hit the button again immediately and the indicator turned off and I went on my way.

What is "O/D"? And what would have happened if I had driven with it "Off" 😕?
Click to expand...

Assuming your car is a 4-speed automatic, that button locks out 4th gear, and turns it into a 3-speed automatic.
 
Originally posted by: Nyati13
Assuming your car is a 4-speed automatic, that button locks out 4th gear, and turns it into a 3-speed automatic.
Click to expand...
I take it that would have lead to a nasty surprise when I tried to merge onto the highway...

Oh, and to answer the questions posed, it's a Corolla w/automatic trans.
 
Originally posted by: AmberClad
Originally posted by: Nyati13
Assuming your car is a 4-speed automatic, that button locks out 4th gear, and turns it into a 3-speed automatic.
Click to expand...
I take it that would have lead to a nasty surprise when I tried to merge onto the highway...

Oh, and to answer the questions posed, it's a Corolla w/automatic trans.
Click to expand...

No, you'd just be wondering why it isn't shifting into the final drive gear and your engine would be revving a bit higher than normal at freeway speeds. It's to keep the transmission from hunting up and down (between drive and overdrive) on long climbs.

You wouldn't have hurt anything but your gas mileage would suffer.
 
You would also burn more fuel with OD locked out..

You would want to lock out overdrive in hilly terrain, and if you were towing a trailer.
 
sometimes on the highway if you want to pass someone but your car isnt giving enough power in the 4th gear, pushing the O/D button will downshift and you could be able to accelerate better.
 
Your right foot should get much better results than pushing the OD button when you want to pass someone.

You'd have to have a pretty light foot to pass someone without dropping out of OD. 😀
 
Originally posted by: Tiamat
sometimes on the highway if you want to pass someone but your car isnt giving enough power in the 4th gear, pushing the O/D button will downshift and you could be able to accelerate better.
Click to expand...

Or you could just push down on the accelerator and get the same result.
 
i like to use the OD button in my rolla as a "boost" button usually when i wanna pass someone on the highway. it makes my engine more noisy and slightly more satisfying 🙂
 
These responses are all over the place. As many have noted, this prevents your overdrive (a gear with a ratio lower than one, but usually used to describe the last gear in an automatic transmission, which, coincidentally, usually have a ratio lower than 1) gear can be switched off with this switch. There are many reasons not to use O/D, and it seems all of them have been hit. The main reason of course is to get the engine to operating temperature. In fact, most auto transmissions will really avoid O/D until the ECT gives a signal that the coolant, and theoretically, the oil, is of a normal temperature.

Some A/T programs (keep in mind this is just software running on very basic hardware as far as "electronic control") even prevents the torque convertor from locking during these cold fluid events, or prevent lockup when the "O/D off" mode is selected. While it is usually very rare that you would need to use this, there are special circumstances where this can save the life of your powertrain quite a bit.
 
Pretty much all been covered but it may be beneficial to disable overdrive not only for hilly roads and passing but also merging onto a highway. So, no nasty surprise, just re-enable for cruising again to conserve fuel. Some manufacturers refer to the O/D Off mode as "Sport" which is as telling as all the detailed info. 😉
 
As has already been stated a few times, stepping on the gas to pass or merge causes the AT to drop out of O/D anyway. Pushing the O/D button to pass or merge makes no sense at all, and does nothing at all that stepping on the gas doesn't already do.

The only reasons to lock out the overdrive will be found in your owner's manual. They are usually A) to stop the transmission from constantly switching in and out of OD on hills, known as "gear hunting", or B)when pulling a trailer. There may be others with some cars, but these are the two most common reasons.

Captain Howdy is also correct about when the engine is cold.

Lockup torque converters also are usually prevented from locking up until things have warmed up. Some of you may have felt that little bump as you cruised along and noticed your tach drop a few hundred revs. That was the converter locking up when your engine got warm enough. Now you are using less fuel at the same speed.

 
Originally posted by: LTC8K6
Sport mode usually raises the shift points, imo.
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True dat. I suppose if the O/D Off switch doesn't do that also then the benefits are indeed more limited. Consult the manual.
 
Think of the O/D off button as a "3" on your shift gate. Because that's exactly what it is. Manufacturers have been grandfathering the 3 position gate for decades now and the O/D off keeps them from having to change that.
 
Originally posted by: LTC8K6
The only reasons to lock out the overdrive will be found in your owner's manual. They are usually A) to stop the transmission from constantly switching in and out of OD on hills, known as "gear hunting", or B)when pulling a trailer. There may be others with some cars, but these are the two most common reasons.
Click to expand...
A) Sounds like it might be useful next time I go through Shenandoah National Park
B) 😕 @ the mental image of a Corolla trying to pull a trailer
 
I shift into O/D at 50 mph and higher.
I use my sport mode rarely. If I have 4 people in the car, for example. The trans will shift at 5k rpm. Whee!
 
Originally posted by: AmberClad
Originally posted by: LTC8K6
The only reasons to lock out the overdrive will be found in your owner's manual. They are usually A) to stop the transmission from constantly switching in and out of OD on hills, known as "gear hunting", or B)when pulling a trailer. There may be others with some cars, but these are the two most common reasons.
Click to expand...
A) Sounds like it might be useful next time I go through Shenandoah National Park
B) 😕 @ the mental image of a Corolla trying to pull a trailer
Click to expand...

I have a tow hitch on my MR2.🙂

Apparently the tow capacity is 1500 lbs, but I don't think I want to tow anything that heavy.
 
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