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 menus: Body Electrical / Body / Data List.
5. Read the display on the Techstream.
   BODY (MAIN BODY ECU RH)
   
   

   Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
   Illumination Rate Info	Illumination information / 0 to 99.99 ms.	0.8 to 22 ms.	-

6. The value of the illumination rate should change in the following range when light shines on the automatic light control sensor or when the automatic light control sensor is covered.

   OK

   0.8 to 22 ms.

   HINT: 

   This is the time taken for the automatic light control sensor to generate one cycle of frequency according to the brightness.

NG → See step   2 

OK → REPLACE MAIN BODY ECU RH (COWL SIDE JUNCTION BLOCK RH) 

1. Disconnect the J74 main body ECU RH connector.
   Fig 1: Identifying J74 And K1 Connector Terminals

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   TEXT IN ILLUSTRATION
   
   

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

2. Disconnect the K1 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
   J74-6 (CLTB) - K1-6 (CLTB)	Always	Below 1 Ω
   J74-5 (CLTS) - K1-5 (CLTS)	Always	Below 1 Ω
   J74-4 (CLTE) - K1-3 (CLTE)	Always	Below 1 Ω
   J74-6 (CLTB) - Body ground	Always	10 kΩ or higher
   J74-5 (CLTS) - Body ground	Always	10 kΩ or higher
   J74-4 (CLTE) - Body ground	Always	10 kΩ or higher

4. Connect the 2 connectors.

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Disconnect the K1 automatic light control sensor connector.
   Fig 2: Identifying K1 Connector Terminals

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   TEXT IN ILLUSTRATION
   
   

   *1	Front view of wire harness connector (to Automatic Light Control Sensor)

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

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   K1-3 (CLTE) - Body ground	Always	Below 1 Ω

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

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   K1-3 (CLTE) - K1-6 (CLTB)	Engine switch on (IG)	11 to 14 V

4. Connect the K1 automatic light control sensor connector.
5. Connect the oscilloscope and check the waveform according to the table below.
   Fig 3: Waveform Graph

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   Standard Voltage

   Tester Connection	Condition	Specified Condition	Tester Range
   K1-3 (CLTE) - K1-5 (CLTS)	Engine switch on (IG), Light control switch in AUTO	Correct waveform is as shown in the illustration	5 V/Division, 5 msec/Division

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

NG → See step   4 

OK → REPLACE MAIN BODY ECU RH (COWL SIDE JUNCTION BLOCK RH)