Od (Overdrive) Off Switch: Description
WARNING: This page is about a different car, the 1995 Jeep Grand Cherokee. However, it is still accessible from the selected car via links, so may be relevant.
The OD (Overdrive) OFF switch is located to the right of steering column, on the instrument panel. The OD OFF switch controls the overdrive operation by delivering an input signal to the TCM. The TCM uses this signal for controlling the operation of the overdrive solenoid on the valve body.