PCM Controlled Lamps

PCM Controlled Lamps Circuit:

Purpose:
The PCM controlled lamps are intended to alert the driver to an operating condition which may require immediate attention.

The lamps operate as follows:

^ The PCM controlled engine coolant temperature warning lamp indicates an overheating condition of the engine.

^ The charging system warning lamp indicates a low system voltage condition if the engine is running.

^ The "Change Oil Soon" lamp indicates that the engine oil is near the end of its useful life.

^ The cruise lamp indicates that the vehicle is being operated in cruise control.

Operation:
The PCM controlled lamps receive battery voltage from the ignition switch through the gage fuse. The PCM controls each lamp by providing a ground path to energize the bulb. The lamps are illuminated whenever the ignition switch is in the "ON" position and the engine is not running. This is for checking the bulbs.

The ECT warning lamp is illuminated while the engine is running if the engine coolant temperature exceeds 124°C (255°F) and no ECT DTC's have been set. The coolant temperature warning lamp is turned "OFF" when the engine coolant temperature goes below 121°C (250°F).

The charging system lamp is illuminated when system voltage falls below 10.6 volts. The lamp will be turned "OFF" when system voltage increases above 11 volts.

The "Change Oil Soon" lamp will be illuminated when the PCM has determined that the engine oil is near the end of its useful life. The PCM makes this decision based on the number of reference pulses it has seen and factors such as engine coolant temperature. The "Change Oil Soon" lamp may also be illuminated is DTC 1619 is set.

Location:
The PCM controlled lamps are located in the Drivers Information Center (DIC) or the Instrument Panel Cluster (IPC).