DTC B1244: Light Sensor Circuit Malfunction [03/2017 - ]: Procedure

1. Clear the DTCs.

   Refer to DTC CHECK / CLEAR [03/2017 - 05/2023] , or refer to DTC CHECK / CLEAR [05/2023 - ]

   Body Electrical > Main Body > Clear DTCs 

2. Turn the engine switch on (IG) and wait for at least 5 seconds or more.
3. Check for DTCs.

   Refer to DTC CHECK / CLEAR [03/2017 - 05/2023] , or refer to DTC CHECK / CLEAR [05/2023 - ]

   Body Electrical > Main Body > Trouble Codes 

   OK

   DTC B1244 is not output.

   Result

   Proceed to
   OK
   NG

Result: 

OK 

USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [03/2017 - 04/2020]  , or refer to  HOW TO PROCEED WITH TROUBLESHOOTING [04/2020 - 05/2023]  , or refer to  HOW TO PROCEED WITH TROUBLESHOOTING [05/2023 - ] 

Result: 

NG 

See step  2

1. Using the Techstream, read the Data List.

   Refer to DATA LIST / ACTIVE TEST [03/2017 - 04/2020] , or refer to DATA LIST / ACTIVE TEST [04/2020 - 05/2023] , or refer to DATA LIST / ACTIVE TEST [05/2023 - ]

2. According to the display on the Techstream, read the Data List and check that the value of Light Sensor Illuminance changes while performing the following:
   1. Turn the light control switch to the AUTO position.
   2. Cover the automatic light control sensor with an opaque object.
   3. Slowly move the opaque object to uncover and then cover the automatic light control sensor.

      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

      The value changes according to the amount the automatic light control sensor is covered.

   Result

   Proceed to
   OK
   NG

Result: 

OK 

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU). Refer to  REMOVAL [03/2017 - 05/2023]  , or refer to  REMOVAL [05/2023 - ] 

Result: 

NG 

See step  3

1. Using an oscilloscope, check the waveform.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a

   Component with harness connected (Main Body ECU [Multiplex Network Body ECU])

   *b

   Waveform

   Measurement Condition

   Tester Connection	Condition	Tool Setting	Specified Condition
   P7-24 (CLTS) - Body ground	Engine switch on (IG), material which blocks light used to cover and then uncover top of automatic light control sensor	2 V/DIV., 10 ms./DIV.	Pulse generation

   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 [03/2017 - 05/2023]  , or refer to  REMOVAL [05/2023 - ] 

Result: 

NG 

See step  4

1. Measure the voltage according to the value(s) in the table below.

   Standard Voltage

   Tester Connection	Switch Condition	Specified Condition
   P7-23 (CLTB) - P7-25 (CLTE)	Engine switch off	Below 1 V
   	Engine switch on (IG)	11 to 14 V

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a	Component with harness connected (Main Body ECU [Multiplex Network Body ECU])

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU). Refer to  REMOVAL [03/2017 - 05/2023]  , or refer to  REMOVAL [05/2023 - ] 

Result: 

OK 

See step  5

1. Disconnect the P7 main body ECU (multiplex network body ECU) connector.
2. Disconnect the Q4 automatic light control sensor connector.
3. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   P7-23 (CLTB) - Q4-1 (CLTB)	Always	Below 1 Ω
   P7-24 (CLTS) - Q4-4 (CLTS)	Always	Below 1 Ω
   P7-25 (CLTE) - Q4-2 (CLTE)	Always	Below 1 Ω
   P7-23 (CLTB) or Q4-1 (CLTB) - Body ground	Always	10 kΩ or higher
   P7-24 (CLTS) or Q4-4 (CLTS) - Body ground	Always	10 kΩ or higher
   P7-25 (CLTE) or Q4-2 (CLTE) - Body ground	Always	10 kΩ or higher

   Result

   Proceed to
   OK
   NG

Result: 

OK 

REPLACE AUTOMATIC LIGHT CONTROL SENSOR. Refer to  REMOVAL [03/2017 - 05/2023]  , or refer to  REMOVAL [05/2023 - ] 

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR