Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual: Meter Illumination does not Dim at Night

DESCRIPTION

In this circuit, the combination meter assembly receives auto dimmer signals from the main body ECU (multiplex network body ECU) via CAN communication. When the combination meter assembly 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 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 headlight dimmer switch assembly is in the tail, head, or AUTO position, the ECU sends an auto dimmer signal to the combination meter assembly.

According to this 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, wire harness, connector, or combination meter assembly.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

PROCEDURE

(a) Check if CAN communication DTCs are output.

Click here

B

GO TO CAN COMMUNICATION SYSTEM

A

(a) Check if lighting system DTCs are output.

w/ Automatic Headlight Beam Level Control System: Click here

w/o Automatic Headlight Beam Level Control System: Click here

B

GO TO DTC B1244

A

(a) Replace the combination meter assembly with a new one.

Click here

OK:

The operation of the combination meter assembly returns to normal.

OK

END

NG

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)