J2000/Sunbird V6-191 3.1L VIN T MFI (1994)
Shift Indicator: Description and Operation
Base Cluster
A lamp lights when the car should be shifted to the next higher gear for better fuel economy. Battery voltage is applied to one side of the bulb. The other
side of the bulb is switched to ground by the Engine Control Module (ECM), which uses engine data such as rpm, vehicle speed, and intake manifold
vacuum to compute an efficient shift point.
