is the overdrive button just a switch that changes the automatic shift points via the ECU?

[Lifer]

does turning OD off cuase the ECU changing the shift points to a higher RPM and vice versa?

 

[Cyberian]

No

 

[MercenaryForHire]

The overdrive button causes a doubling in horsepower and massive surges in forward momentum. Speeds of 200mph+ are not unheard of. Use with caution.

- M4H

 

[NikPreviousAcct]

Overdrive is a "pseudo-gear." It's hard for me to explain because I don't fully understand the mechanics of it, but the way it has been explained to me is that overdrive is a gear that doesn't actually exist.

 

[Heisenberg]

No. It lets the tranny shift into the highest (overdrive) gear. Typically fourth gear on a modern automatic. Also usually lets the torque converter lockup if the cars has a lockup converter.

 

[Lifer]

actually i meant turning OD off would result in the ECU changing the shift points to a higher RPM.

 

[zixxer]

Originally posted by: Heisenberg
No. It lets the tranny shift into the highest (overdrive) gear. Typically fourth gear on a modern automatic.

Yes.

Also, in some cars it makes the automatic shift point higher.

the reason it is called overdrive is that in *some* cars (not all) that gear makes the tire turn more than one time for every time the engine turns one time.. or something like that...

 

[Heisenberg]

Originally posted by: Lifer
actually i meant turning OD off would result in the ECU changing the shift points to a higher RPM.

No, it won't.