Headlight Dimmer Switch Circuit [10/2018 - 11/2021]: Procedure
WARNING: This page does not describe the selected car, but rather 12 other vehicles, including the 2024 Lexus RC 350, 2024 Lexus RC 300, 2023 Lexus RC 350, 2023 Lexus RC 300, and 2022 Lexus RC 350. However, it is still accessible from the selected car via links, so may be relevant.
- READ VALUE USING TECHSTREAM
- Connect the Techstream to the DLC3.
- Turn the engine switch on (IG).
- Turn the Techstream on.
- Enter the following menus: Body Electrical / Main Body / Data List.
- Read the Data List according to the display on the Techstream.
Body Electrical > Main Body > Data List
Tester Display Measurement Item Range Normal Condition Diagnostic Note Dimmer SW Dimmer switch high position signal OFF or ON OFF: Dimmer switch in low position
ON: Dimmer switch in high or high flash position- Passing Light SW Dimmer switch high flash position (pass) signal OFF or ON OFF: Dimmer switch not in high flash position
ON: Dimmer switch in high flash position- Auto Light SW Light control switch AUTO position signal OFF or ON OFF: Light control switch not in AUTO position
ON: Light control switch in AUTO position- Head Light SW (Head) Light control switch head position signal OFF or ON OFF: Light control switch not in head position
ON: Light control switch in head position- Head Light SW (Tail) Light control switch tail position signal OFF or ON OFF: Light control switch not in tail or head position
ON: Light control switch in tail or head position- Body Electrical > Main Body > Data List
Tester Display Dimmer SW Passing Light SW Auto Light SW Head Light SW (Head) Head Light SW (Tail) OK
Normal conditions listed above are displayed.
Result
Proceed to OK NG
Result:
OK
PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to PROBLEM SYMPTOMS TABLE [10/2018 - 09/2020] , or refer to PROBLEM SYMPTOMS TABLE [09/2020 - ]
Result:
NG
See step 2
- INSPECT HEADLIGHT DIMMER SWITCH ASSEMBLY
- Remove the headlight dimmer switch assembly.
Refer to REMOVAL [09/2014 - ]
- Inspect the headlight dimmer switch assembly.
Refer to INSPECTION [10/2018 - 11/2021]
Result
Proceed to OK NG
Result:
NG
REPLACE HEADLIGHT DIMMER SWITCH ASSEMBLY. Refer to REMOVAL [09/2014 - ]
Result:
OK
See step 3
- Remove the headlight dimmer switch assembly.
- CHECK HARNESS AND CONNECTOR (HEADLIGHT DIMMER SWITCH ASSEMBLY - MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU))
- Disconnect the O2 main body ECU (multiplex network body ECU) connector.
- Measure the resistance according to the value(s) in the table below.
Standard Resistance
Tester Connection Condition Specified Condition O22-18 (HU) - O2-24 (HU) Always Below 1 Ω O22-21 (HF) - O2-10 (HF) Always Below 1 Ω O22-22 (T) - O2-22 (TAIL) Always Below 1 Ω O22-23 (H) - O2-12 (HEAD) Always Below 1 Ω O22-24 (A) - O2-8 (A) Always Below 1 Ω O22-18 (HU) or O2-24 (HU) - Body ground Always 10 kΩ or higher O22-21 (HF) or O2-10 (HF) - Body ground Always 10 kΩ or higher O22-22 (T) or O2-22 (TAIL) - Body ground Always 10 kΩ or higher O22-23 (H) or O2-12 (HEAD) - Body ground Always 10 kΩ or higher O22-24 (A) or O2-8 (A) - Body ground Always 10 kΩ or higher O22-19 (EL) - Body ground Always Below 1 Ω Result
Proceed to OK NG
Result:
OK
REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU). Refer to REMOVAL [09/2014 - ]
Result:
NG
REPAIR OR REPLACE HARNESS OR CONNECTOR