Malfunction Indicator Lamp: Description and Operation

The instrument panel mounted ``Check Engine'' or ``Service Engine Soon'' lamp is used to alert the operator of malfunctions within the C-3 system.

- When the ignition is ON with the engine stopped, the lamp is illuminated as a bulb check.

- When the engine is running, the lamp will be illuminated whenever the ECM senses a system malfunction.

- In addition, the lamp is used to access trouble codes stored in the ECM trouble code memory.