Meter Illumination is Always Dark: Description

In this circuit, the meter CPU receives auto dimmer signals from the main body ECU using the CAN communication system (CAN V1 Bus). When the meter CPU receives an auto dimmer signal, it dims the meter illumination (warning and indicator lights). The main body ECU determines whether it is daytime, twilight, or nighttime based on the waveform transmitted from the automatic light control sensor. If the main body ECU determines that it is daytime, the ECU does not send an auto dimmer signal. Therefore, the meter illumination will not dim even if the driver accidentally turns the light control switch to the tail or head position in daytime.

HINT: 

When the meter illumination is always dark, there may be a malfunction in the automatic light control sensor, main body ECU, CAN communication system, harness or connector, or combination meter assembly.