Overdrive Switch: Description and Operation

TRANSMISSION CONTROL SWITCH (TSC) AND TRANSMISSION CONTROL INDICATOR LAMP (TCIL)
The Transmission Control Switch (TCS) is a momentary contact switch that allows the driver to cancel operation of 5th (overdrive) gear.

The Powertrain Control Module (PCM) uses the shift solenoids to disengage/disable 5th gear operation and activate the coast clutch.

At the same time the PCM illuminates the Transmission Control Indicator Lamp (TCIL), to notify the driver that 5th gear is canceled.

When the TCS is pressed again, 5th gear operation is enabled' the coast clutch is released and the TCIL is turned off.

Whenever the ignition is cycled (vehicle shut off then started again) the TCS Is turned off and 5th gear will be enabled, even if the TCS had been on when the ignition was shut off.

The Transmission Control Indicator Lamp (TCIL) Is located in the instrument panel and is labeled O/D OFF It is illuminated in conjunction with the Transmission Control Switch (TCS).