LIGHTING SYSTEM, Diagnostic DTC:B1244

DTC Code DTC Name
B1244 Light Sensor Circuit Malfunction

DESCRIPTION

Note

If the main body ECU (multiplex network body ECU) is replaced, refer to Service Bulletin.

The automatic light control sensor detects ambient light. The sensor creates an electrical signal based on the amount of light detected, and sends the signal to the main body ECU (multiplex network body ECU). The main body ECU (multiplex network body ECU) turns on or off the headlights and taillights according to the signal.

DTC No. DTC Detecting Condition Trouble Area
B1244

  • Malfunction in automatic light control sensor

  • Open or short in automatic light control sensor circuit

  • Automatic light control sensor

  • Harness or connector

  • Main body ECU (multiplex network body ECU)

WIRING DIAGRAM

A01G4RWE05

INSPECTION PROCEDURE

Note

If the main body ECU (multiplex network body ECU) is replaced, refer to Service Bulletin.

PROCEDURE


  1. READ VALUE USING GTS


    1. Connect the GTS to the DLC3.

    2. Turn the engine switch on (IG).

    3. Turn the GTS on.

    4. Enter the following menus: Body Electrical / Main Body / Data List.

    5. Read the display on the GTS.

      Main Body
      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      Illumination Rate info Illumination rate information/0.00 ms to 2162.65 ms Value is output according to ambient light level -
      OK
      Normal condition listed above is displayed.

    NG

    CHECK HARNESS AND CONNECTOR (MAIN BODY ECU - AUTOMATIC LIGHT CONTROL SENSOR) Click here

    OK

    REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) Click here

  2. CHECK HARNESS AND CONNECTOR (MAIN BODY ECU - AUTOMATIC LIGHT CONTROL SENSOR)


    1. Disconnect the J1 automatic light control sensor connector.

    2. Disconnect the H10 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
      H10-22 (CLTE) - J1-3 (CLTE) Always Below 1 Ω
      H10-21 (CLTS) - J1-5 (CLTS) Always Below 1 Ω
      H10-20 (CLTB) - J1-6 (CLTB) Always Below 1 Ω
      H10-22 (CLTE) - Body ground Always 10 kΩ or higher
      H10-21 (CLTS) - Body ground Always 10 kΩ or higher
      H10-20 (CLTB) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  3. INSPECT MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)


    1. A01G5M8E04
      Text in Illustration
      *a

      Component with harness connected

      (Main Body ECU (Multiplex Network Body ECU))

      Reconnect the H10 main body ECU (multiplex network body ECU) connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      H10-20 (CLTB) - H10-22 (CLTE) Engine switch off Below 1 V
      Engine switch on (IG) 11 to 14 V
      Standard Resistance
      Tester Connection Condition Specified Condition
      H10-22 (CLTE) - Body ground Always Below 1 Ω

    NG

    REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) Click here

    OK

  4. INSPECT AUTOMATIC LIGHT CONTROL SENSOR


    1. A01G8M8E07

      Reconnect the J1 automatic light control sensor connector.

    2. Connect an oscilloscope to the automatic light control sensor connector.

      Text in Illustration
      *a

      Component with harness connected

      (Automatic Light Control Sensor)
    3. A01G6C5E01

      Check the waveform.

      OK
      Tester Connection Tool Setting Condition Specified Condition
      J1-3 (CLTE) - J1-5 (CLTS) 5 V/DIV., 5 ms./DIV. Engine switch on (IG), light control switch in AUTO position Correct waveform is as shown

      Tech Tips

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


    NG

    REPLACE AUTOMATIC LIGHT CONTROL SENSOR Click here

    OK

    REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) Click here