Overdrive-Off Indicator Lamp

The overdrive-off indicator lamp gives the driver an indication that the automatic transmission overdrive has been locked out. The lamp is controlled by the Powertrain Control Module (PCM) on a hard wired circuit to instrument cluster.

The PCM receives an input from the momentary overdrive lockout switch, which is located on the end of the automatic transmission gearshift selector lever. The PCM uses the overdrive lockout switch input, along with numerous other sensor inputs and its internal programming to decide whether the overdrive-off indicator lamp should be on or off. The PCM then turns the lamp on or off by controlling the ground path for the lamp control circuit.