Overdrive Switch: Description and Operation

O/D Main Switch & O/D Off Indicator Light

The O/D main switch contacts go open when the switch is pushed in and go closed when it is pushed out. If O/D main switch is at OFF position, the O/D OFF indicator light lights up, and the ECM prohibits shifting overdrive.

While driving uphill with cruise control activated, in order to minimize gear shifting and provide smooth cruising overdrive may be prohibited temporarily under some conditions.

The cruise control ECU sends O/D cut signals to the ECM as necessary and the ECM cancels overdrive shifting until these signals are discontinued.