Overdrive Switch: Description and Operation

Overdrive On/Off Switch

DESCRIPTION

The transaxle control system is equipped with an Overdrive On/Off button used to inhibit fourth gear operation. The O/D OFF lamp on the instrument panel will illuminate when fourth gear has been "locked out". If the Overdrive On/Off button is depressed during fourth gear operation, a 4-3 downshift will occur. The Overdrive On/Off button should be used when descending hills or during city driving to increase engine braking. The Overdrive On/Off switch is located on the end of the selector lever.



OPERATION

The O/D ON/OFF Switch grounds or opens Transmission Control Module (TCM) input circuit ZY39 (GN/O) to force the TCM to either enable or disable overdrive. The TCM then either grounds or removes ground from the O/D ON/OFF Switch Lamp to indicate that the transaxle overdrive is enabled or cancelled.