RAM 3500 Truck 4WD V10-8.0L VIN W (1997)
Shift Indicator: Description and Operation
SYSTEM OPERATION
Certain vehicles equipped with a transmission have an upshift indicator lamp. The upshift indicator lamp gives an indication when the driver
should shift to the next highest gear for the best fuel economy One side of the indicator lamp bulb receives ignition-switched battery feed. The
ground path for the other side of the lamp bulb is switched by the Powertrain Control Module (PCM).
The PCM will turn the lamp off after three to five seconds if the upshift is not performed. The lamp will remain off until the vehicle stops
accelerating and is brought back into the range of lamp operation, or until the transmission is shifted into another gear.
The indicator lamp is normally on when the ignition switch is in the On position, and is turned off when the engine is started. The PCM uses inputs
from many sensors and its internal programming to decide whether the engine speed and load conditions are proper for a transmission upshift.
