With reference to Automatic transmission, What is this small button called OD Lock near the shift? What is the function? Should it be pressed down during normal driving?
overdrive.. if you shut it off, car wont go into overdrive,, that is economy gear like 5th gear of manual. . leave it on,, car automatically decides to engage it.
i might mix it upbut i think idea is that if it is pressed, the car revs more in a particular gear, i.e. tries to get the best out of it.Otherwise gears are changed early as per throttle position.
rashid bhai please explain i also need some correction.
as far my understnading goes, levin said right, it's not Long( L ), it's over drive(O/D), meant for fuel efficiency.also it changes gears earlier than normal.
saqib bhai: an example: by default, car is driven with OD on, but if yr driving to murree, you may not want yr car getting its into 5th gear or OD because you wont be able to accelerate it in time if needed, so switch off OD function.
same applies coming down hill.. to reduce brakes heatup. if yr still experiencing powerloss, on uneven roads,, shift to 2nd gear, or "2", and reduce speed.
and when u switch off O/D a light shows "OD OFF" right?i tested one and with OD OFF light coming car was pulling more in one gear hebce not economical. i was testing it for economy on CNG point of view. it had a complaint of excessive gas consumption. i told him to drive with OD on i.e no light showing and car improved on consumption.
no light in dash cluster,,means O/D is in operation by default. Yes. there is only o/d "off" light.. no o/d "on" light in corolla at least!.
@levin, if OD is like a fifth gear, then why it is not placed in shifter?? Or is it electronically controlled??
electronically controlled,, but option is there to keep it off using the "off" button.
spectra auto also has OD off light and it is on by default
@kdiesel: it's not like 5th gear, but one can say,it changes gear and does not push/rev engine up to the range where o/d off works. makes sense
Levin is correct in terms of the OD function. However it is not always the 5th gear. Most cars like corolla etc are 4 speed auto. OD is always the highest gear. So in a 5speed auto OD will be the 5th gear, in 4speed auto like corolla etc OD will be the 4th gear. Somoeone asked about higher revs, well for that some cars have a "power" button. It makes the gears shift at higher rpm's.
ty benz for correction. 5th gear was the closest term i could think of that time. maybe topgear example is better than 5th
@levin bhai, not a correction. merely some addition to your perfectly given definition.
So the conclusion is that I should keep the button pressed until I require more power in a particular gear, especially at hilly areas. At that stage I should release it for the cluster to show O/D off. Right?
here's a simpler way to put it. whenever you don't want the highest gear engaged, regardless how and where u're driving, just turn O/D off. how and when you use it is upto you.
Ok.......done about OD...What if the car has both OD and ECT ???
it locks the torque convertor's input and output shafts...there is no slippage..only required at high wheel speed to lower the engine speed..improves fuel economy...driver feels only like another upshift taking place...if button is not pressed car will not go into overdrive reardless of speed..if button is pressed car will move onto overdrive 5th gear on reaching a suitable road speed...in some cars like Civic Prosmatec the button is not there and car moves to overdrive automatically at about 100km/h and 2500 rpm
