CHECK ENGINE indicator lamp: Notes

Fig 1: Engine Indicator Lamp

Courtesy of SAAB-SCANIA OF AMERICA, INC.

Fig 2: Engine Indicator Lamp Wiring

Courtesy of SAAB-SCANIA OF AMERICA, INC.

The CHECK ENGINE lamp (MIL) warns the driver when a fault occurs in the engine management system.

The lamp is supplied with current in the main instrument unit and grounded by the MIU's control module. The Trionic T7 continuously sends bus information CHECK ENGINE, unit ON/OFF.

On receiving CHECK ENGINE ON, the control module grounds the output of the lamp, which then lights up.

On cars for certain markets the TCM lights the CHECK ENGINE lamp.

With the ignition ON the lamp remains on until the engine starts. If there are no faults the lamp will go out.

If the Trionic T7 changes the status of the message to CHECK ENGINE OFF, the lamp will go out.