Prizm L4-1800cc 1.8L DOHC (1993)
Overdrive Switch: Description and Operation
The "OVERDRIVE" switch is located on the manual selector and allows the driver to select the overdrive gear. When the "OVERDRIVE" switch
is depressed, the PCM receives a signal indicating the position of the "OVERDRIVE" switch. With this signal present, the PCM adds a 4th gear to
the transaxle shift schedule above 3rd gear. When the "OVERDRIVE" switch is released, the PCM returns the transaxle to its normal 3-speed shift
schedule. The overdrive gear can only be selected with the manual selector in "D" (drive) position.