Dakota 4WD V6-239 3.9L Magnum (1996)
Overdrive Switch: Description and Operation
CIRCUIT OPERATION
Automatic transmission equipped vehicles may 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.
If overdrive is currently enabled, it is disabled when the operator depresses the overdrive switch. Conversely, if the operator already disabled
overdrive, it is enabled when the switch is depressed.
Circuit T6 from the overdrive switch connects to cavity C13 of the PCM and provides the overdrive signal.
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 G5 from fuse 16 in the fuse block.
When the headlamps or parking lamps are ON, circuit E2 from fuse 13 in the fuse block powers the illumination lamp in the overdrive switch.
Circuit E1 from the headlamp switch feeds fuse 13.
Circuit Z1 provides ground for the illumination lamp in the overdrive switch. The grounding point for circuit Z1 is the instrument panel left
support.
