DTC B1244: Light Sensor Circuit Malfunction: Procedure

1. Clear the DTCs. Refer to DTC CHECK / CLEAR .
2. Check for DTCs. Refer to DTC CHECK / CLEAR .

   OK

   DTC B1244 output does not occur.

NG → See step   2 

OK → See step   8 

1. Using the Techstream, read the Data List. Refer to DATA LIST / ACTIVE TEST .
   MAIN BODY
   
   

   Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
   Illumination Rate Info	Illumination rate information / 0 ms. to 99.99 ms.	Value is output according to ambient light levels	-

   OK

   Normal condition listed above is displayed.

NG → See step   3 

OK → See step   6 

1. Disconnect the F9 main body ECU connector.
2. Disconnect the G2 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
   F9-22 (CLTE) - G2-3 (CLTE)	Always	Below 1 Ω
   F9-21 (CLTS) - G2-5 (CLTS)	Always	Below 1 Ω
   F9-20 (CLTB) - G2-6 (CLTB)	Always	Below 1 Ω
   F9-22 (CLTE) - Body ground	Always	10 kΩ or higher
   F9-21 (CLTS) - Body ground	Always	10 kΩ or higher
   F9-20 (CLTB) - Body ground	Always	10 kΩ or higher

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Reconnect the F9 main body ECU connector.
   Fig 1: Main Body ECU Connector Terminal Identification

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

   Standard Voltage

   Tester Connection	Switch Condition	Specified Condition
   F9-20 (CLTB) - F9-22 (CLTE)	Ignition switch off	Below 1 V
   	Ignition switch ON	11 to 14 V

   TEXT IN ILLUSTRATION
   
   

   *a	Component with harness connected (Main Body ECU)

NG → See step   6 

OK: Go to next step 

1. Reconnect the G2 automatic light control sensor connector.
   Fig 2: Automatic Light Control Sensor Connector

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Connect an oscilloscope to the automatic light control sensor connector.
3. Check the waveform.

   OK

   Tester Connection	Tool Setting	Switch Condition	Specified Condition
   G2-3 (CLTE) - G2-5 (CLTS)	5 V/DIV., 5 ms./DIV.	Ignition switch ON, headlight dimmer switch in AUTO position	Correct waveform is as shown

   Fig 3: Identifying Waveform

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   TEXT IN ILLUSTRATION
   
   

   *a	Component with harness connected (Automatic Light Control Sensor)

   HINT: 

   If the ambient light becomes brighter, width A becomes narrower.

NG → See step   7 

OK → See step   6