DTC B1244: Light Sensor Circuit Malfunction: Procedure

1. Connect the Techstream to the DLC3.
2. Turn the engine switch on (IG).
3. Turn the Techstream on.
4. Enter the following menu items: Body Electrical / Main Body / Data List.
5. Read the display on the 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 → See step   5 

1. Disconnect the H3 automatic light control sensor connector.
   Fig 1: Identifying H3 Automatic Light Control Sensor & F13 Main Body ECU (Multiplex Network Body ECU) Connector Terminals

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Disconnect the F13 main body ECU (multiplex network body ECU) connector.
3. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   F13-22 (CLTE) - H3-3 (CLTE)	Always	Below 1 Ω
   F13-21 (CLTS) - H3-5 (CLTS)	Always	Below 1 Ω
   F13-20 (CLTB) - H3-6 (CLTB)	Always	Below 1 Ω
   F13-22 (CLTE) - Body ground	Always	10 kΩ or higher
   F13-21 (CLTS) - Body ground	Always	10 kΩ or higher
   F13-20 (CLTB) - Body ground	Always	10 kΩ or higher

   TEXT IN ILLUSTRATION
   
   

   *1	Front view of wire harness connector (to Automatic Light Control Sensor)
   *2	Front view of wire harness connector (to Main Body ECU (Multiplex Network Body ECU))

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Reconnect the F13 main body ECU (multiplex network body ECU) connector.
   Fig 2: Identifying F13 Main Body ECU (Multiplex Network Body ECU) Connector Terminals

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

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   F13-20 (CLTB) - F13-22 (CLTE)	Engine switch off	Below 1 V
   	Engine switch on (IG)	11 to 14 V

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   F13-22 (CLTE) - Body ground	Always	Below 1 Ω

   TEXT IN ILLUSTRATION
   
   

   *1	Component with harness connected (Main Body ECU (Multiplex Network Body ECU))

NG → See step   5 

OK: Go to next step 

1. Reconnect the H3 automatic light control sensor connector.
   Fig 3: Identifying H3 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
   
   

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

3. Check the waveform.

   OK

   Tester Connection	Tool Setting	Condition	Specified Condition
   H3-3 (CLTE) - H3-5 (CLTS)	5 V/DIV., 5 ms./DIV.	Engine switch on (IG), light control switch in AUTO position	Correct waveform is as shown

   Fig 4: Identifying Waveform Graph

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   HINT: 

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

NG → See step   6 

OK → See step   5