The glow indicator lamp is used to notify the driver when the glow plug is in operation. The glow indicator lamp are shut off when the battery voltage is low. The duration of preheating and illumination of glow indicator lamp are entirely controlled by the injection computer depending on the engine operating conditions.

Preheating begins as soon as the ignition is switched on. Postheating consists of alternately supplying the preheating resistors after the engine has been started. But preheating warning lamp is not illuminated during preheating.

All glow phases except the pre and the start-ready glow are switched off at engine off.

And then the glow indicator lamp is illuminated for at least the time during the pre-glow and start-ready phase by the ECM.

If the glow indicator lamp circuit generates threshold value, the ECM judged this as a fault and DTC is set.