Malfunction Indicator Lamp (Mil).

Fig 1: Identifying MIL Lamp Signal Communication

Courtesy of VOLVO CARS CORPORATION

The malfunction indicator lamp (MIL) only lights in the driver information module (DIM) (5/1) if certain specific emissions related diagnostic trouble codes (DTCs) are stored in the engine control module (ECM) (4/46) or transmission control module (TCM) (4/28).

The engine control module (ECM), respectively, transmission control module (TCM) transmits the signal to the central electronic module (CEM) (4/56) via the controller area network (CAN) and the central electronic module (CEM) transmits it on to the driver information module (DIM) that lights the lamp.