D 250 Pickup L6-359 5.9L DSL (1992)
Overdrive Override Switch: Description and Operation
LOCATION
The overdrive override switch is located in the instrument panel.
PURPOSE
On vehicles equipped with an automatic transmission with overdrive, the electronic controller uses the overdrive solenoid to control the 3-4
overdrive upshift.
OPERATION
When the overdrive override switch is closed, the transmission is allowed to enter overdrive if all conditions are met. If the switch is opened, by
the driver pressing it, the transmission will not be able to enter overdrive.
The overdrive override switch circuit contains two other switches; a transmission thermo-switch and a coolant temperature switch. If any of the
three switches is open, the transmission will not be able to enter overdrive. If any of these switches is opened while the transmission is in
overdrive, the transmission will shift down out of overdrive.
