DTC B1244: Light Sensor Circuit Malfunction: Procedure

1. Connect the Techstream to the DLC3.
2. Turn the engine switch on (IG) and turn the Techstream on.
3. The value of the illumination rate should change in the following range when light contacts the light sensor or when the light sensor is covered.

   OK

   0.008 to 0.022 seconds

   HINT: 

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

OK → REPAIR MULTIPLEX NETWORK BODY ECU 

NG: Go to next step 

1. Disconnect the K67 multiplex network body ECU connector.
   Fig 1: Checking Wire Harness (Multiplex Network Body ECU - Automatic Light Control Sensor)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Disconnect the L1 sensor connector.
3. Measure the resistance of the wire harness side connectors.

   Standard resistance

   Tester Connection	Specified Condition
   K67-6 (CLTB) - L1-6 (CLTB)	Below 1 Ω
   K67-4 (CLTE) - L1-3 (CLTE)	Below 1 Ω
   K67-5 (CLTS) - L1-5 (CLTS)	Below 1 Ω
   K67-6 (CLTB) - Body ground	10 kΩ or higher
   K67-4 (CLTE) - Body ground	10 kΩ or higher
   K67-5 (CLTS) - Body ground	10 kΩ or higher

NG → REPAIR OR REPLACE HARNESS AND CONNECTOR 

OK: Go to next step 

1. Disconnect the sensor.
   Fig 2: Identifying Automatic Light Control Sensor

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Connect the voltmeter's positive (+) lead to terminal 6 and the negative (-) lead to terminal 3.
3. Measure the voltage of the connector.

   Standard voltage

   Tester Connection	Condition	Specified Condition
   L1-3 (CLTE) - L1-6 (CLTB)	Always	10 to 14V

4. Measure the resistance of the connector.

   Standard resistance

   Tester Connection	Condition	Specified Condition
   L1-3 (CLTE) - Body ground	Always	Below 1 Ω

5. Connect the L1 automatic light control sensor connector.
6. Check the waveform of the connector.
   Fig 3: Identifying Signal Waveform

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   Standard voltage

   Tester Connection	Condition	Specified Condition	Tester Range
   L1-3 (CLTE) - L1-5 (CLTS)	Engine switch on (IG), Headlight dimmer switch in AUTO	Correct waveform is as shown	5 V Division, 5 msec/Division

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

   If the result is not as specified, replace the automatic light control sensor.

NG → REPLACE AUTOMATIC LIGHT CONTROL SENSOR 

OK → REPLACE MULTIPLEX NETWORK BODY ECU