Overdrive Off Indicator

WARNING: This page is about a different car, the 2003 Pontiac Vibe. However, it is still accessible from the selected car via links, so may be relevant.

With the ignition switch in the RUN position, voltage is applied through the Gage Fuse (10-amp) to the OD/OFF indicator light. Whenever the overdrive switch (located on the shifter) is released to the OFF position, system voltage is applied through the closed contacts of the overdrive switch to ground. When this occurs, the OD/OFF indicator light in the instrument cluster will illuminate and the Powertrain Control Module (PCM) will simultaneously receive a low voltage signal at the O/D ON/OFF input. With a low voltage input, the PCM will disable the overdrive function. Whenever the overdrive switch is depressed to the RUN position, the overdrive switch opens. When this occurs, the O/D/OFF indicator light in the instrument cluster will go out and the PCM will simultaneously receive a high voltage signal at the O/D ON/OFF input. With a high voltage input, the PCM will enable the overdrive function and the transaxle is permitted to shift into overdrive when appropriate.