GM Service Manual Online
For 1990-2009 cars only

Purpose

All vehicles are equipped with a Low Oil Level warning lamp and Temp Lamp Hot Light. The Low Oil Level lamp indicates when a low oil level condition has been detected. The Temp Lamp Hot indicates when the engine coolant has reached a temperature that can cause engine damage.

Oil Level Switch

The oil level switch is an assembly containing a reed switch and a magnetic float. When the oil level is normal, the float rests near the reed switch, causing the switch to close. When the oil level is low, the float rests away from the reed switch, causing the contacts to open.

The oil level switch is mounted in the engine oil pan. The oil level switch supplies a ground signal to the PCM when the engine oil level is above a specific level. If the engine oil level falls below this level, the oil level switch opens and the PCM sends a signal through UART serial data to the IPC to illuminate the Check Oil telltale lamp.

Temp Lamp

The Temp Lamp will illuminate when the engine is running and the engine coolant temperature exceeds 123°C (253°F). The Temp Lamp will turn OFF whenever the engine coolant temperature falls below 120°C (248°F). The Temp Lamp will not illuminate if DTCs P0117 or P0118 are set.