Meter Illumination Is Always Dark

METER / GAUGE / DISPLAY: METER / GAUGE SYSTEM: Meter Illumination is Always Dark
- Meter Illumination is Always Dark

DESCRIPTION

In this circuit, the meter CPU receives auto dimmer signals from the main body ECU (multiplex network body ECU) using the CAN communication system (CAN No. 1 Bus). When the meter CPU receives an auto dimmer signal, it dims the meter illumination (warning and indicator lights). The main body ECU (multiplex network 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 (multiplex network body ECU) determines that it is nighttime and the light control switch is in the tail, head or AUTO position, the ECU sends an auto dimmer signal. According to the signal, the combination meter assembly dims the meter illumination.

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

WIRING DIAGRAM





INSPECTION PROCEDURE

NOTICE:
If the meter is always dark even if the light control rheostat is operated, refer to "Operating Light Control Rheostat does not Change Light Brightness" Operating Light Control Rheostat Does Not Change Light Brightness.

PROCEDURE

1. CHECK CAN COMMUNICATION SYSTEM

(a) Check if a CAN communication DTC is output Diagnosis System.

Result





B -- GO TO CAN COMMUNICATION SYSTEM How to Proceed With Troubleshooting
A -- Continue to next step.

2. CHECK DTC (LIGHT SENSOR CIRCUIT)

(a) Check if DTC B1244 is output Reading and Clearing Diagnostic Trouble Codes.

Result





B -- GO TO LIGHTING SYSTEM B1244
A -- Continue to next step.

3. CHECK OPERATION (HEATER CONTROL PANEL)

(a) Turn the engine switch on (IG).

(b) Turn the light control switch to the tail, head, or AUTO position.

(c) Cover the automatic light control sensor.

(d) Check the heater control panel illumination.

Result





HINT
Both the heater control panel and the combination meter assembly illumination dim according to the dimmer signal. Therefore, when only the meter illumination is always dark, there may be a malfunction in the combination meter assembly.

B -- REPLACE COMBINATION METER ASSEMBLY Removal
A -- Continue to next step.

4. CHECK OPERATION (AUTOMATIC LIGHT CONTROL SYSTEM)

(a) Turn the engine switch on (IG).

(b) Turn the light control switch to the AUTO position.

(c) Cover the automatic light control sensor.

(d) Check the taillights and low beam headlights.

OK:

The taillights and low beam headlights come on.

(e) Uncover the automatic light control sensor.

(f) Check the low beam headlights and taillights.

OK:

The taillights and low beam headlights go off.

Result





B -- CHECK LIGHTING SYSTEM How To Proceed With Troubleshooting
A -- Continue to next step.

5. REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

(a) Replace the main body ECU (multiplex network body ECU) with a new or normally functioning one Removal.

(b) Check the operation of the combination meter assembly.

OK:

The operation of the combination meter assembly returns to normal.

HINT
The meter CPU controls the meter illumination based on an auto dimmer signal from the main body ECU (multiplex network body ECU). When the meter illumination is always dark (very dim), it may be due to the main body ECU (multiplex network body ECU) sending an auto dimmer signal to the meter CPU because of a malfunction in the main body ECU (multiplex network body ECU).

NG -- REPLACE COMBINATION METER ASSEMBLY Removal

OK -- END