Meter Illumination Does Not Dim At Night
METER / GAUGE / DISPLAY: METER / GAUGE SYSTEM: Meter Illumination does not Dim at Night
- Meter Illumination does not Dim at Night
DESCRIPTION
In this circuit, the meter ECU 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 ECU 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 does not dim at night, there may be a malfunction in the automatic light control sensor, main body ECU (multiplex network body ECU), CAN communication system, harness or connector, or combination meter assembly.
WIRING DIAGRAM
INSPECTION PROCEDURE
HINT
* The automatic light control sensor sensitivity can be customized Customize Parameters.
* Setting the meter illumination to maximum brightness prevents the meter illumination from dimming when the light control switch is changed to the tail or head position at night, or changed to the AUTO position. Therefore, check the meter illumination setting before proceeding to the following steps.
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 CONTROL SENSOR CIRCUIT)
(a) Check if DTC B1244 is output Reading and Clearing Diagnostic Trouble Codes.
Result:
B -- GO TO LIGHTING SYSTEM [1][2]B Code Charts
A -- Continue to next step.
3. CHECK OPERATION (HEATER CONTROL PANEL)
(a) Turn the power switch on (IG).
(b) Turn the light control switch to the tail, head, or AUTO position.
(c) Cover the light control switch.
(d) Check the heater control panel illumination.
Result:
HINT
Both the heater control panel and combination meter assembly illumination dim according to the dimmer signal. Therefore, when only the meter illumination does not dim at night, replace 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 power 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 low beam headlights and taillights go off.
Result:
B -- CHECK LIGHTING SETTING Customize Parameters
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 a known good one Removal.
OK:
The operation of the combination meter assembly returns to normal.
HINT
The meter ECU controls the meter illumination based on an auto dimmer signal from the main body ECU (multiplex network body ECU). If the meter does not dim when the light control switch is in the tail, head, or AUTO position at night, it may be for either of 2 reasons. The first reason is that the main body ECU (multiplex network body ECU) does not send an auto dimmer signal. The second is that the meter ECU does not dim the meter illumination even though the meter ECU receives an auto dimmer signal.
NG -- REPLACE COMBINATION METER ASSEMBLY Removal
OK -- END