DTC B1244: Light Sensor Circuit Malfunction: Procedure

1. Connect Techstream to the DLC3.
2. Turn the ignition switch on (IG).
3. Turn Techstream on.
4. Select the following menu items: Body Electrical / Main Body / Data List.
5. Read the display on Techstream.
   MAIN BODY:
   
   

   Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
   Illumination Rate	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   2 

OK → REPLACE MAIN BODY ECU (INSTRUMENT PANEL JUNCTION BLOCK) 

1. for Manual A/C
   1. Disconnect the F1 automatic light control sensor connector.
      Fig 1: Checking Harness And Connector (Main Body ECU - Automatic Light Control Sensor)

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   2. Disconnect the D7 main body ECU connector.
   3. Measure the resistance according to the value(s) in the table below.

      Standard resistance

      Tester Connection	Condition	Specified Condition
      D7-18 (CLTE) - F1-6 (CLTE)	Always	Below 1 Ω
      D7-19 (CLTS) - F1-4 (CLTS)	Always	Below 1 Ω
      D7-20 (CLTB) - F1-3 (CLTB)	Always	Below 1 Ω
      D7-18 (CLTE) - Body ground	Always	10 kΩ or higher
      D7-19 (CLTS) - Body ground	Always	10 kΩ or higher
      D7-20 (CLTB) - Body ground	Always	10 kΩ or higher

2. for Automatic A/C
   1. Disconnect the F2 automatic light control sensor connector.
      Fig 2: Measuring Resistance Of Automatic Light Control Sensor Connector

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   2. Disconnect the D7 main body ECU connector.
   3. Measure the resistance according to the value(s) in the table below.

      Standard resistance

      Tester Connection	Condition	Specified Condition
      D7-18 (CLTE) - F2-3 (CLTE)	Always	Below 1 Ω
      D7-19 (CLTS) - F2-5 (CLTS)	Always	Below 1 Ω
      D7-20 (CLTB) - F2-6 (CLTB)	Always	Below 1 Ω
      D7-18 (CLTE) - Body ground	Always	10 kΩ or higher
      D7-19 (CLTS) - Body ground	Always	10 kΩ or higher
      D7-20 (CLTB) - Body ground	Always	10 kΩ or higher

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Reconnect the main body ECU connector.
2. Measure the voltage and resistance according to the value(s) in the table below.
   Fig 3: Measuring Voltage Of Main Body ECU (Instrument Panel Junction Block Assembly)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   Standard voltage

   Tester Connection	Condition	Specified Condition
   D7-20 (CLTB) - D7-18 (CLTE)	Ignition switch off	Below 1 V
   	Ignition switch on (IG)	11 to 14 V

   Standard resistance

   Tester Connection	Condition	Specified Condition
   D7-18 (CLTE) - Body ground	Always	Below 1 Ω

NG → REPLACE MAIN BODY ECU (INSTRUMENT PANEL JUNCTION BLOCK) 

OK: Go to next step 

1. for Manual A/C:
   1. Reconnect the automatic light control sensor connector.
      Fig 4: Inspecting Automatic Light Control Sensor

      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	Condition	Specified Condition
      F1-6 (CLTE) - F1-4 (CLTS)	5 V/DIV., 5 ms./DIV.	Ignition switch on (IG), light control switch in AUTO	Correct waveform is as shown

      Fig 5: Identifying Waveform

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   HINT: 

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

2. for Automatic A/C:
   1. Reconnect the automatic light control sensor connector.
      Fig 6: Checking 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	Condition	Specified Condition
      F2-3 (CLTE) - F2-5 (CLTS)	5 V/DIV., 5 ms./DIV.	Ignition switch on (IG), light control switch in AUTO	Correct waveform is as shown

      Fig 7: Identifying Waveform

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   HINT: 

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

NG → REPLACE AUTOMATIC LIGHT CONTROL SENSOR 

OK → REPLACE MAIN BODY ECU (INSTRUMENT PANEL JUNCTION BLOCK)