DTC B1244: Light Sensor Circuit Malfunction [08/2019 - ]: Procedure

1. Clear the DTCs.

   Refer to DTC CHECK / CLEAR [08/2019 - ]

2. Turn the engine switch on (IG).
3. Turn on the headlights using the light control switch.
4. Check for DTCs.

   Refer to DTC CHECK / CLEAR [08/2019 - ]

   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 [08/2019 - ] 

Result: 

NG 

See step  2

1. Using the Techstream, read the Data List.

   Refer to DATA LIST / ACTIVE TEST [08/2019 - ]

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.
      MAIN BODY
      
      

      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	-

      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 [08/2019 - ] 

Result: 

NG 

See step  3

1. Disconnect the H133 main body ECU (multiplex network body ECU) connector.
2. Disconnect the H148 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
   H133-19 (CLTB) - H148-1 (CLTB)	Always	Below 1 Ω
   H133-20 (CLTS) - H148-4 (CLTS)	Always	Below 1 Ω
   H133-21 (CLTE) - H148-2 (CLTE)	Always	Below 1 Ω
   H133-19 (CLTB) or H148-1 (CLTB) - Body ground	Always	10 kΩ or higher
   H133-20 (CLTS) or H148-4 (CLTS) - Body ground	Always	10 kΩ or higher
   H133-21 (CLTE) or H148-2 (CLTE) - Body ground	Always	10 kΩ or higher

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  4

1. Disconnect the H148 automatic light control sensor connector.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

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

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

   Standard Voltage

   Tester Connection	Switch Condition	Specified Condition
   H133-19 (CLTB) - H133-21 (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 [08/2019 - ] 

Result: 

OK 

See step  5

1. Inspect the automatic light control sensor.

   Refer to ON-VEHICLE INSPECTION [08/2019 - ]

   Result

   Proceed to
   OK
   NG

Result: 

OK 

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU). Refer to  REMOVAL [08/2019 - ] 

Result: 

NG 

REPLACE AUTOMATIC LIGHT CONTROL SENSOR. Refer to  REMOVAL [08/2017 - ]