2500 4x4 Pickup V8-318 5.2L Magnum (1995)
Overdrive Switch: Description and Operation
CONSTRUCTION
Automatic transmission equipped vehicles have an overdrive switch. The operator disables or enables overdrive when the switch is depressed.
The overdrive switch consists of a switch connected to the Powertrain Control Module (PCM), an illumination lamp, and an overdrive ON/OFF
indicator lamp.
OPERATION
If overdrive is currently enabled, it is disabled when the operator presses the overdrive switch. Conversely, if the operator already disabled
overdrive, it is enabled when the switch is pressed.
Circuit T6 from the overdrive switch connects to cavity 10 of the PCM and provides the overdrive signal. Circuit Z3 provides ground for the
switch.
The PCM turns the overdrive ON/OFF indicator lamp ON or OFF by providing a ground for the lamp on circuit T18. Power for the lamp is
supplied by circuit F12 from the fuse block.
When the headlamps or parking lamps are ON, circuit E2 from fuse 13, a 5 amp, in the fuse block powers the illumination lamp in the overdrive
switch. Circuit E1 from the headlamp switch feeds fuse 13.
Circuit Z3 provides ground for the illumination lamp in the overdrive switch.