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	Illumination rate information / 0 ms to 99.99 ms	Value output according to ambient light levels	-

   OK

   Normal condition listed above is displayed.

NG → See step   3 

OK → See step   6 

1. Disconnect the G47 main body ECU connector.
2. Disconnect the H19 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
   G47-22 (CLTE) - H19-3 (CLTE)	Always	Below 1 Ω
   G47-21 (CLTS) - H19-5 (CLTS)	Always	Below 1 Ω
   G47-20 (CLTB) - H19-6 (CLTB)	Always	Below 1 Ω
   G47-22 (CLTE) - Body ground	Always	10 kΩ or higher
   G47-21 (CLTS) - Body ground	Always	10 kΩ or higher
   G47-20 (CLTB) - Body ground	Always	10 kΩ or higher

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Remove the driver side junction block with its connectors still connected. Refer to REMOVAL .
   Fig 1: Identifying G47 Driver Side Junction Block Connector Terminals

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Measure the voltage according to the value(s) in the table below.

   Standard Voltage

   Tester Connection	Switch Condition	Specified Condition
   G47-20 (CLTB) - G47-22 (CLTE)	Engine switch off	Below 1 V
   	Engine switch on (IG)	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. Remove the automatic light control sensor with its connector still connected. Refer to REMOVAL .
   Fig 2: Identifying H19 Automatic Light Control Sensor Connector Terminals

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Connect an oscilloscope to the automatic light control sensor connector.
   TEXT IN ILLUSTRATION
   
   

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

3. Check the waveform.

   OK

   Tester Connection	Tool Setting	Switch Condition	Specified Condition
   H19-3 (CLTE) - H19-5 (CLTS)	5 V/DIV., 5 ms./DIV.	Engine switch on (IG), headlight dimmer switch in AUTO position	Correct waveform is as shown

   Fig 3: Identifying Waveform Graph

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   HINT: 

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

NG → See step   7 

OK → See step   6