DTC B1244: Light Sensor Circuit Malfunction [09/2014 - 10/2018]: Procedure
WARNING: This page does not describe the selected car, but rather 9 other vehicles, including the 2018 Lexus RC 350, 2018 Lexus RC 300, 2017 Lexus RC 350, 2017 Lexus RC 300, and 2017 Lexus RC 200t. 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 Light Sensor Illuminance Light control sensor illuminance 0 to 8191 lx Value is output according to ambient light level - Body Electrical > Main Body > Data List
Tester Display Light Sensor Illuminance OK
Normal condition listed above is displayed.
Result
Proceed to OK NG
Result:
OK
REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU). Refer to REMOVAL [09/2014 - ]
Result:
NG
See step 2
- CHECK HARNESS AND CONNECTOR (MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) - AUTOMATIC LIGHT CONTROL SENSOR)
- Disconnect the P1 automatic light control sensor connector.
- 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 O2-21 (CLTE) - P1-2 (CLTE) Always Below 1 Ω O2-20 (CLTS) - P1-4 (CLTS) Always Below 1 Ω O2-19 (CLTB) - P1-1 (CLTB) Always Below 1 Ω O2-21 (CLTE) - Body ground Always 10 kΩ or higher O2-20 (CLTS) - Body ground Always 10 kΩ or higher O2-19 (CLTB) - Body ground Always 10 kΩ or higher Result
Proceed to OK NG
Result:
NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
Result:
OK
See step 3
- INSPECT MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)
- Reconnect the O2 main body ECU (multiplex network body ECU) connector.
*a Component with harness connected
(Main Body ECU (Multiplex Network Body ECU)) - Measure the voltage according to the value(s) in the table below.
Standard Voltage
Tester Connection Condition Specified Condition O2-19 (CLTB) - O2-21 (CLTE) Engine switch off Below 1 V Engine switch on (IG) 11 to 14 V Result
Proceed to OK NG
Result:
NG
REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU). Refer to REMOVAL [09/2014 - ]
Result:
OK
See step 4
- Reconnect the O2 main body ECU (multiplex network body ECU) connector.
- INSPECT AUTOMATIC LIGHT CONTROL SENSOR
- Reconnect the P1 automatic light control sensor connector.
*a Component with harness connected
(Automatic Light Control Sensor) - Connect an oscilloscope to the automatic light control sensor connector.
- Check the waveform.
OK
Tester Connection Tool Setting Condition Specified Condition P1-2 (CLTE) - P1-4 (CLTS) 2 V/DIV., 10 ms./DIV. Engine switch on (IG), light control switch in AUTO position Correct waveform is as shown HINT:
The communication waveform changes according to the surrounding brightness.
Result
Proceed to OK NG
Result:
OK
REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU). Refer to REMOVAL [09/2014 - ]
Result:
NG
REPLACE AUTOMATIC LIGHT CONTROL SENSOR. Refer to REMOVAL [09/2014 - ]
- Reconnect the P1 automatic light control sensor connector.