Check Oil Level
WARNING: This page is about a different car, the 2002 Oldsmobile Aurora and 2001 Oldsmobile Aurora. However, it is still accessible from the selected car via links, so may be relevant.
The DIC displays the CHECK OIL LEVEL 5 message when the PCM detects low engine oil level, and the signal circuit is high. The PCM sends a class 2 message to the DIC indicating the engine oil level.