Malfunction Indicator Lamp: Description and Operation

NOTE: Malfunction Indicator Lamp (MIL), previously called Check Engine Lamp (CEL).

PURPOSE
Indicates immediate service of engine control system is required.

Informs driver that he has entered "Limp-In" mode, lamp ON while vehicle is being driven.

Displays Diagnostic Trouble Codes (DTC's), stored in memory.

OPERATION
Illuminates for three seconds when ignition switch is turned ON, (for bulb test).

Illuminates if Powertrain Control Module (PCM) receives an out of range input from a monitored circuit, or, (for vehicles with California emissions), from an emission related device.

- Signals that can set Malfunction Indicator Lamp are battery voltage input, charging system, Manifold Absolute Pressure (MAP), sensor, Throttle Position Sensor (TPS), Engine Coolant Temperature (ECT) sensor.

Can be used to display any DTC's stored in memory, SEE POWERTRAIN MANAGEMENT/COMPUTERS AND CONTROL SYSTEMS/TESTING AND INSPECTION.