Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual: Diagnosis System

DIAGNOSIS SYSTEM

DESCRIPTION

Air conditioning system data and Diagnostic Trouble Codes (DTCs) can be read through the Data Link Connector 3 (DLC3) of the vehicle. When the system seems to be malfunctioning, use the Techstream to check for malfunctions and perform troubleshooting.

CHECK DLC3

Check the DLC3.

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LIST OF OPERATION METHODS

By operating each of the air conditioning control switches as shown in the diagram below, it is possible to enter diagnostic check mode.

INDICATOR CHECK

(a) Turn the engine switch off.

(b) Turn the engine switch on (IG) and press the radio receiver assembly (A/C control panel) AUTO and recirculation/fresh switches simultaneously within 5 seconds.

(c) The indicator check is automatically performed when panel diagnosis is activated. Check that the indicators light up and go off 4 times at 1 second intervals continuously.

SENSOR CHECK (DTC CHECK)

(a) Perform the indicator check.

HINT:

After the indicator check is completed, the system enters DTC check mode automatically.

(b) Read the DTCs displayed on the display.

NOTICE:

In sensor check mode, which is automatically entered after indicator check mode, troubleshooting may be partially performed. Be sure to perform the sensor check again.

HINT:

Refer to Diagnostic Trouble Code Chart for details of the codes.

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(c) If the DTCs are difficult to read because they change automatically, Press the driver side TEMP up switch to display the steps one at a time so that they can be read easily. The items are displayed step by step each time the driver side TEMP up switch is pressed.

HINT:

Press the OFF switch to finish panel diagnosis.

(d) Clear DTCs.

(1) During the sensor check, press the front defroster switch and rear defogger switch simultaneously.